DOI: https://doi.org/10.21203/rs.3.rs-2571732/v1
Objective: To investigate similarities and differences in immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in kids with two primary immunodeficiency diseases, Wiskott-Aldrich syndrome (WAS) and chronic granulomatous disease (CGD).
Method: We retrospectively analyzed the lymphocyte subpopulations (CD3+ T cells, CD4+ T cells, CD8+ T cells, NK cells, B cells) and various immunoglobulin counts (IgM, IgA, IgG, C3, C4) on Days 15, 30, 100, 180 and 360 after transplantation in 70 children with WAS and 48 children with CGD who underwent allo-HSCT at the Transplantation Center of the Department of Hematology-Oncology, Children's Hospital of Chongqing Medical University from January 2007 to December 2020, and we compared and analyzed the differences in the immune reconstitution process between the two groups.
Results: ① On Day 15 posttransplantation, the WAS group had significantly higher NK cell counts than the CGD group. On Days 30, 100 and 180 posttransplantation, the WAS group had notably higher CD4+ T-cell counts than the CGD group. On Days 100 and 180 posttransplantation, the WAS group had considerably higher B-cell counts than the CGD group. ② On Day 15 posttransplantation, NK cell counts in the WAS group were considerably higher than those in the CGD group among kids aged 1-3 years who underwent transplants. On Days 30 and 180 posttransplantation, the WAS group had notably higher CD4+ T-cell counts than the CGD group among kids aged 1-3 years who underwent transplants. On Day 180 posttransplantation, B-cell counts in the WAS group were consistently higher than those in the CGD group among kids aged 1-3 years who underwent transplants. On Day 360 posttransplantation, the CGD group had notably higher CD8+ T-cell counts than the WAS group among kids aged 1-3 years who underwent transplants. ③ On Days 15 and 30 posttransplantation, kids who underwent non-umbilical cord blood transplantation (non-UCBT) had significantly higher B-cell counts than kids who underwent UCBT in the WAS group. On Days 100 and 180 posttransplantation, children who underwent UCBT had apparently higher B-cell counts than children who underwent non-UCBT in the WAS group. On Day 30 posttransplantation, kids who underwent UCBT had notably higher CD3+ T-cell counts than kids who underwent non-UCBT in the WAS group. On Days 30, 100 and 180 posttransplantation, kids who underwent UCBT had obviously higher CD4+ T-cell counts than kids who underwent non-UCBT in the WAS group. On Day 360 posttransplantation, children who underwent UCBT had markedly higher NK cell counts than children who underwent non-UCBT in the WAS group. ④ On Day 15 posttransplantation, NK cell counts were probably higher in the non-cord-blood-transplanted kids with WAS compared to the non-cord-blood-transplanted kids with CGD. On Days 30 and 100 posttransplantation, CD4+ T-cell counts weresignificantly higher in the non-cord-blood-transplanted kids with WAS compared to the non-cord-blood-transplanted kids with CGD. On Day 30 posttransplantation, B-cell counts were notably higher in the non-cord-blood-transplanted kids with WAS compared to the non-cord-blood-transplanted kids with CGD. ⑤ On Day 100 after allo-HSCT, the CGD group had higher C3 levels than the WAS group. On Day 360 after allo-HSCT, the CGD group had higher IgA and C4 levels than the WAS group.
Conclusion: ① During the immune reconstitution process, the WAS group had significantly higher lymphocyte subpopulation counts than the CGD group after transplantation, indicating that the rate of immunity recovery was faster in kids within the WAS group compared to those kids within the CGD group, which may be related to the type of graft (percentage undergoing UCBT) and the different primary diseases themselves. ② During B-cell reconstitution in kids with WAS, kids who underwent non-UCBT had notably higher B-cell counts than kids who underwent UCBT at Days 15 and 30 posttransplantation, and kids who underwent UCBT had notably higher B-cell counts than kids who underwent non-UCBT at Days 100 and 180 posttransplantation, indicating that cord blood has strong B-cell reconstitution potential after allo-HSCT.
Wiskott-Aldrich syndrome (WAS) and chronic granulomatous disease (CGD) are two different types of primary immunodeficiency diseases (PIDs). WAS, a syndromic combined immunodeficiency disease marked by an impaired lymphocyte lineage, is an X-linked invisible genetic disorder that usually affects males and is carried by females. WAS is prompted by mutations in WAS genes encoding the WAS protein (WASp), in which WASp is expressed only in the hematopoietic system and plays an important role in hematopoietic cell differentiation and migration, cell signaling, immune synapse formation, and lymphocyte apoptosis. As many as 300 mutations in WAS genes are known, resulting in varying degrees of defective WASp, and this can contribute to a variety of abnormal immune cell functions and lead to a variety of clinical phenotypes [1–2]. WAS features an increased incidence of congenital thrombocytopenia, eczema, recurrent infections, autoimmune diseases, and malignancies [3]. Without radical treatment, most patients suffer from recurrent infections and long-term immunodeficiency, which affects the quality of life and life expectancy. CGD, an X-linked or autosomal recessive sickness, was brought on by mutations in the gene encoding a subunit of the NADPH oxidase complex, resulting in an inherited defect in phagocytosis [4]. Patients with CGD are prone to recurrent bacterial and fungal infections, excessive inflammatory responses, and immune dysregulation due to defective oxygen radical production by phagocytes, which cannot effectively clear infections.
Currently, allogeneic hematopoietic stem cell transplantation (allo-HSCT) offers the potential to cure PIDs such as WAS and CGD in the long term, along with the prophylactic use of antibacterial and antifungal drugs and improved symptomatic control of infections, autoimmune diseases and inflammatory complications. Since the first successful allo-HSCT was reported in 1968 for the treatment of kids with WAS [5], allo-HSCT has gradually developed into a major treatment tool for patients with PIDs [6–7]. The level of immune reconstitution after transplantation is an important factor affecting the prognosis, and nonspecific immune reconstitution is mostly rapid within weeks, while specific immune reconstitution takes 1 year or longer [8–9], during which time children are highly susceptible to life-threatening serious infections such as bacterial, fungal, and viral infections. It can be seen that robust and timely immune reconstitution is essential for immune protection against opportunistic infections. At present, there are no studies on the differences in immune recovery after transplantation in kids with different immunodeficiency diseases, and there is limited published information on immune reconstitution after allo-HSCT in patients with WAS and CGD. Therefore, our study summarized and analyzed the immune reconstitution characteristics of 70 kids with WAS and 48 kids with CGD within 1 year after undergoing allo-HSCT and summarized transplant-related information in both groups to explore the differences in immune reconstitution in kids with both diseases.
1. Cases: A total of 118 kids with two PIDs who underwent allo-HSCT at the Transplantation Center of the Department of Hematology-Oncology, Children's Hospital of Chongqing Medical University from January 2007 to December 2020 were included in the study. Inclusion criteria: (1) having a documented immune reconstitution process on Day 100 posttransplantation or after Day 100 posttransplantation; (2) receiving nondepleted T cells as a pretreatment regimen; and (3) undergoing hematopoietic reconstitution. Exclusion criteria: (1) kids with failed transplants, failure to achieve hematopoietic reconstitution, or death within 3 months posttransplantation and (2) no record of an immune reconstitution process on or after Day 100 posttransplantation. In the WAS group, the median time to implantation of neutrophils was Day 11 (5–36 days) posttransplantation, and the median time to implantation of platelets was Day 20 (5–83 days) posttransplantation. In the CGD group, the median time to implantation of neutrophils was Day 11 (9–17 days) posttransplantation, and the median time to implantation of platelets was Day 11 (1–35 days) posttransplantation.
2. Lymphocyte classification and immunoglobulin monitoring: Changes in lymphocyte subsets, including CD3 + T cells, CD4 + T cells, CD8 + T cells, NK cells (CD56+) and B cells (CD19+), were monitored on Days 15, 30, 100, 180 and 360 after allo-HSCT using flow cytometry. Immunofluorescence detection of immunoglobulins: The levels of various types of immunoglobulins, including IgM, IgA, IgG, C3, and C4, were detected on Days 15, 30, 100, 180, and 360 after allo-HSCT using an immunoturbidimetric assay.
3. Statistical processing: SPSS 26.0 was used for statistical processing. The Mann‒Whitney U test was used for continuous variables, the chi-square test or Fisher exact test was used for categorical variables, and Student's t test was used for numerical variables in the comparison of the clinical characteristics of the children. When analyzing the absolute counts of lymphocyte subpopulations in children with both diseases at different time points, data that did not satisfy the normal distribution were analyzed using the Mann‒Whitney nonparametric test, and statistical descriptions were performed using the median and interquartile range (Q25 to Q75). Plots were processed using GraphPad Prism 9. P < 0.05 (two-sided) was considered a statistically significant difference.
1. Basic information and transplant characteristics of children: The basic characteristics of the 118 children are shown in Table S1. Among them, kids with WAS and CGD were statistically different in terms of the age at transplant, nucleated cell infusion volume, CD34 + cell infusion volume, graft type, and ATG use. The transplantation age of children in the WAS group was apparently younger compared with that in the CGD group; the nucleated cell infusion volume and CD34 + cell infusion volume in the CGD group had been greater compared with that in the WAS group; the proportion of UCBT in the WAS group was apparently higher compared with that in the CGD group; and the proportion of patients receiving ATG pretreatment in the CGD group used to be considerably greater compared with that in the WAS group. There were also differences in infection between the WAS and CGD groups before transplantation: the number of CMV infections in the WAS group was higher than that in the CGD group, and the numbers of EBV and fungal infections in the CGD group were higher than those in the WAS group. All children in the WAS and CGD groups were male, 1 child in the WAS group was transplanted with CB + BM, and the rest were transplanted with a single graft. As of December 31, 2022, one child in the WAS group died of respiratory and circulatory failure due to severe pulmonary infection in the 11th month after allo-HSCT (2013/7/2), and the remaining 117 children survived. The median follow-up time was 78.1 months for the surviving children in the WAS group (69 children) and 52 months for the surviving children in the CGD group (48 children).
2. Reconstruction of lymphocyte subsets in the WAS and CGD groups (shown in Table S2 and Fig.S1 (A, B, C, D, E)).
On Day 15 after allo-HSCT, the WAS group had significantly higher NK cell counts than the CGD group [233.47 (59.69-395.78) ×107/L vs. 129.25 (28.41-217.53) ×107/L, P = 0.022]. On Days 30, 100 and 180 after allo-HSCT, the WAS group had notably higher CD4 + T-cell counts than the CGD group [305.47 (117.81–427.50) ×107/L vs. 134.77 (62.74-244.97) ×107/L, P < 0.001], [312.80 (127.00-546.95) ×107/L vs. 148.64 (111.06-282.32) ×107/L, P = 0.005], [397.93 (228.15-631.74) ×107/L vs. 179.85(120.61-366.11)×107/L, P = 0.004]. On Days 100 and 180 after allo-HSCT, the WAS group had considerably higher B-cell counts than the CGD group [32.28 (12.24-231.74) ×107/L vs. 18.43 (8.39–55.82) ×107/L, P = 0.027], [132.05 (43.04–418.20) ×107/L vs. 37.32 (14.96-132.36) ×107/L, P = 0.002].
3. The reconstitution of lymphocyte subsets and analysis of graft types in children aged 1–3 years in the WAS and CGD groups (shown in Table S3 and Table S4, Fig.S2 (A, B, C, D, E)).
We selected the age group with the largest number of transplants in WAS and CGD groups, i.e., children aged 1–3 years who underwent allo-HSCT, and we analyzed the reconstruction of lymphocyte subpopulations in these children at different time points after allo-HSCT. The results are as follows.
On Day 15 posttransplantation, NK cell counts in the WAS group were considerably higher than those in the CGD group among children aged 1–3 years who underwent transplants [265.60 (61.98-375.97) ×107/L vs. 113.46 (26.85-223.29) ×107/L, P = 0.050]. On Days 30 and 180 posttransplantation, the WAS group had notably higher CD4 + T-cell counts than the CGD group among kids aged 1–3 years who underwent transplants [325.80 (143.29–465.00) ×107/L vs. 133.93 (63.94-241.75) ×107/L, P = 0.011], [308.20 (201.21–526.40) ×107/L vs. 174.39 (129.96-282.96) ×107/L, P = 0.025]. On Day 180 posttransplantation, B-cell counts in the WAS group were consistently higher than those in the CGD group among children aged 1–3 years who underwent transplants [131.20 (95.70-266.64) ×107/L vs. 28.02 (13.10-104.23) ×107/L, P = 0.003]. On Day 360 posttransplantation, the CGD group had notably higher CD8 + T-cell counts than the WAS group among kids aged 1–3 years who underwent transplants [1278.28 (674.62-3540.85)×107/L vs. 578.54 (454.63-803.18)×107/L, P = 0.021].
In addition, the study compared the graft types of children in the WAS and CGD groups who underwent allo-HSCT at the age of 1–3 years. The results showed that there were no significant differences in graft type between children in the WAS and CGD groups who underwent allo-HSCT at the age of 1–3 years (P = 0.100).
4. Reconstruction of lymphocyte subsets after umbilical cord blood transplantation (UCBT) and non-UCBT in the WAS group (shown in Table S5 and Fig.S3 (A, B, C, D, E)).
On Days 15 and 30 posttransplantation, children who underwent non-UCBT had significantly higher B-cell counts than children who underwent UCBT in the WAS group [15.55 (5.69–60.66) ×107/L vs. 0.48 (0.00-1.41) ×107/L, P < 0.001], [14.63 (8.48–25.46) ×107/L vs. 1.24 (0.20–2.23) ×107/L, P < 0.001]. On Days 100 and 180 posttransplantation, children who underwent UCBT had apparently higher B-cell counts than children who underwent non-UCBT in the WAS group [250.80 (125.50-552.30) ×107/L vs. 24.99 (11.18–89.16) ×107/L, P = 0.001], [445.600 (131.20-712.71) ×107/L vs. 96.60 (39.24-191.95) ×107/L, P < 0.001]. On Day 30 posttransplantation, kids who underwent UCBT had notably higher CD3 + T-cell counts than kids who underwent non-UCBT in the WAS group [1427.40 (961.69-2080.18) ×107/L vs. 914.92 (282.17-1614.18) ×107/L, P = 0.026]. On Days 30, 100 and 180 posttransplantation, kids who underwent UCBT had obviously higher CD4 + T-cell counts than kids who underwent non-UCBT in the WAS group [507.04 (218.31-705.45) ×107/L vs. 244.39 (97.21-401.69) ×107/L, P = 0.003], [466.82 (289.30-734.57) ×107/L vs. 260.25 (118.72-479.53) ×107/L, P = 0.038], [571.29 (384.52–832.00) ×107/L vs. 308.20 (168.48–488.70) ×107/L, P = 0.002]. On Day 360 posttransplantation, children who underwent UCBT had markedly higher NK cell counts than children who underwent non-UCBT in the WAS group [668.62 (515.46-901.64) ×107/L vs. 346.13 (229.56-488.45) ×107/L, P = 0.007].
5. Reconstruction of lymphocyte subsets after non-UCBT in the WAS and CGD groups (shown in Table S6 and Fig.S4 (A, B, C, D, E)).
On Day 15 posttransplantation, NK cell counts were probably higher in the non-cord-blood-transplanted kids with WAS compared to the non-cord-blood-transplanted kids with CGD [233.47 (63.09-438.78) ×107/L vs. 129.69 (28.02-222.26) ×107/L, P = 0.043]. On Days 30 and 100 posttransplantation, CD4 + T-cell counts were significantly higher in the non-cord-blood-transplanted kids with WAS compared to the non-cord-blood-transplanted kids with CGD [244.39 (97.21-401.69) ×107/L vs. 139.22 (63.26-253.12) ×107/L, P = 0.024], [260.25 (118.72-479.53) ×107/L vs. 148.64 (111.06-282.32) ×107/L, P = 0.049]. On Day 30 posttransplantation, B-cell counts were notably higher in the non-cord-blood-transplanted kids with WAS compared to the non-cord-blood-transplanted kids with CGD [14.63 (8.48–25.46) ×107/L vs. 4.51 (2.21–11.52) ×107/L, P < 0.001].
6. Immunoglobulin reconstitution in the WAS and CGD groups (shown in Table S7 and Fig.S5 (A, B, C, D, E, F)).
On Day 100 after allo-HSCT, the CGD group had higher C3 levels than the WAS group [0.9000 (0.8075–1.0750) ×g/L vs. 0.7650 (0.6900-0.9825) ×g/L, P = 0.002]. On Day 360 after allo-HSCT, the CGD group had higher IgA and C4 levels than the WAS group [0.4930 (0.3595–0.76975) ×g/L vs. 0.4030 (0.2740–0.5320) ×g/L, P = 0.033], [0.2000 (0.1475-0.2200) ×g/L vs. 0.150 (0.130–0.180) ×g/L, P = 0.004]. There was no statistically significant change in immunoglobulin levels between the both groups on Days 15, 30 and 180 after allo-HSCT (P > 0.05). Among the patients who underwent allo-HSCT in our center, due to the influence of regular infusions of gamma globulin (IVIG), the IgG levels of the WAS and CGD groups of patients at various time points posttransplantation are not of comparative value.
7. Infection and aGVHD after allo-HSCT in the WAS and CGD groups (shown in Table S8)
In this paper, children in the WAS and CGD groups were divided into different age groups (< 1 year, 1–3 years, 3–5 years, and > 5 years), and we compared the numbers of posttransplantation infections and occurrences of aGVHD in children in different age groups. In children younger than 1 year of age, the numbers of posttransplantation EBV and fungal infections were higher in the CGD group than in the WAS group. In children 1–3 years of age, the numbers of posttransplantation EBV and CMV infections were higher in the CGD group than in the WAS group. In children older than 5 years, the number of posttransplantation fungal infections was higher in the CGD group than in the WAS group.
Over the past 20 years, our center has performed allo-HSCT for nearly 200 children with immunodeficiency diseases, which has greatly improved the survival and prognosis of these patients. The effect of transplantation depends primarily on the hematopoietic and immune reconstitution capacity of the donor's hematopoietic stem cells in the recipient, which suggests that posttransplantation hematopoietic and immune reconstitution is the basis of successful allo-HSCT. It was in this study that we compared for the first time the immune reconstitution data of WAS and CGD within 1 year after allo-HSCT. We first analyzed the reconstitution of lymphocyte subsets after transplantation in children with WAS and CGD by flow cytometry and found that the reconstitution of lymphocyte subsets posttransplantation was different in both groups. At Day 15 after allo-HSCT, the WAS group had significantly higher NK cell counts compared to the CGD group. At Days 30, 100, and 180 posttransplantation, the WAS group had notably higher CD4 + T-cell counts compared to the CGD group. At Days 100 and 180 posttransplantation, the WAS group had considerably higher B-cell counts compared to the CGD group. In general, immune reconstitution in the WAS group was faster than that in the CGD group after allo-HSCT.
WAS group has faster immune reconstitution than CGD group after allo-HSCT, which may be attributed to different factors inherent in the different primary diseases or to some modifiable factors (e.g., graft type). To investigate the reasons for the faster immune reconstitution in the WAS group than in the CGD group, we compared the basic clinical characteristics of the two groups of children (Table S1), including the age at transplantation, graft mononuclear cell (MNC) content and CD34 + cell count, human leukocyte antigen (HLA) matching, ABO blood group, graft type, donor type, pretreatment regimen, acute graft versus host disease (aGVHD) prophylaxis regimen, and aGVHD occurrence. The graft type, graft MNC content, CD34 + cell count, and pretreatment regimen were significantly different between the WAS and CGD groups. It is noteworthy that in this study, there were more umbilical cord blood transplantations (UCBTs) in the WAS group and only one UCBT in the CGD group, which led to differences in graft type between the two groups. More children with WAS underwent UCBT, while cord blood (CB) contained fewer cells, which led to differences in graft MNC content and CD34 + cell counts between kids with WAS and kids with CGD. The lower number of cells in CB, and therefore children who underwent UCBT did not use ATG during pretreatment, led to differences in the use of ATG during the pretreatment regimen in the two groups of children. Consequently, differences in graft type between the WAS and CGD groups of children in this study resulted in differences in graft MNC content and CD34 + cell count as well as pretreatment regimen. In the present paper, we focused on the effect of two variables (transplantation age and graft type) on immune recovery in those with WAS and CGD.
In this paper, the median age of kids who received transplants in the WAS group was significantly younger than that of kid in the CGD group, so does the age at transplantation contribute to the difference in immune reconstitution between the two groups of kids? Patient age at transplantation has been recognized as a prime determinant of the speed and quality of immune reconstitution since the start of this research [10]. It was shown that patients younger than 8 years who underwent allo-HSCT exhibited higher absolute lymphocyte counts at Day 30 posttransplantation and better CD4 + T-cell recovery at Day 100 posttransplantation [11]. Another previous study reported that younger recipient age was associated with higher total and memory B-cell counts after transplantation, pointing to a potential role of nonhematopoietic/microenvironmental factors [12]. We divided the WAS and CGD groups into different age groups (< 1 year, 1–3 years, 3–5 years, > 5 years); selected the age group with the largest number of children, i.e., children who underwent transplantation at 1–3 years; and compared their posttransplantation lymphocyte subpopulation reconstitution (Table S3). The results showed a higher level of lymphocyte subpopulation reconstitution in children who underwent transplants at 1–3 years in the WAS group compared to children who underwent transplants at 1–3 years in the CGD group. The finding was generally consistent with the findings of immune reconstitution in children of all ages in the WAS and CGD groups. Considering the effect of graft type, a comparison was also made between the graft types of children in the age group 1–3 years (Table S4), and it was observed that there was no significant difference between the graft types of children in the WAS and CGD groups within this age group. Therefore, the results of this study differ from the previous view that age affects immune reconstitution. Results of this research indicate that the age at transplantation has little effect on immune reconstitution in young children with WAS and CGD.
We next investigated the effect of graft type on immune reconstitution in WAS and CGD groups. As more patients in the WAS group underwent UCBT, we divided the patients in the WAS group into two groups according to UCBT and non-UCBT and compared the differences in lymphocyte subpopulation levels between the two groups after transplantation (Table S5). The results showed that the lymphocyte subpopulation counts were higher in the non-cord-blood-transplanted children in the WAS group compared to the non-cord-blood-transplanted children in the CGD group. The proportion of children who underwent UCBT was higher in the WAS group than in the CGD group. Moreover, immune reconstitution was faster in children who underwent UCBT than in children who underwent non-UCBT in the WAS group. Therefore, it is possible that UCBT may be partly responsible for the faster immune reconstitution in the WAS group compared to the CGD group.
During immune reconstitution in children who did and did not undergo UCBT in the WAS group, we also found children who underwent non-UCBT had higher B-cell counts than children who underwent UCBT in the WAS group at Days 15 and 30 after allo-HSCT, but children who underwent UCBT had higher B-cell counts than children who underwent non-UCBT in the WAS group on Days 100 and 180 after allo-HSCT. This phenomenon seems to indicate that CB has strong B-cell reconstitution potential after allo-HSCT. Previous studies suggested that B-cell recovery after UCBT was faster than after sibling peripheral blood transplantation because of better B-lymphocyte reconstitution in vitro and in vivo in CB containing a higher proportion of progenitor cells [13–16]. Several articles report an advantage of CB over bone marrow (BM) or peripheral blood stem cells in terms of B-cell recovery time and B-cell differentiation [17–19]. A previous study concluded that the total number of B cells, non-transformed memory cells, and transformed memory B cells was higher in the CB compared to the BM or peripheral blood [17]. Children with WAS have a strong B-cell reconstitution potential after UCBT, which can also be explained by the higher number of B lymphocyte progenitor cells in CB compared to BM [20].
To exclude the effect of UCBT, we additionally did a comparison of the counts of lymphocyte subpopulations in non-cord-blood-transplanted children in the WAS and CGD groups (Table S6). Coincidentally, lymphocyte counts were also higher in the non-cord-blood-transplanted children in the WAS group compared to the non-cord-blood-transplanted children in the CGD group. Therefore, UCBT cannot fully explain the faster immune reconstitution in children in the WAS group than in children in the CGD group. Many previous studies have reported delayed recovery of T-cell immune subsets after UCBT [15, 21–22]. In this paper, CD4 + T-cell reconstitution used to be faster in kids who underwent UCBT than in kids who underwent non-UCBT in the WAS group, and this contradicts previous views and confirms our view that there may be an effect of the primary disease itself in addition to the effect of CB.
Immunoglobulins were used as a crude proxy for B-cell counts and function, and the present study also analyzed IgM, IgA, IgG, C3, and C4 serum levels after allo-HSCT in WAS and CGD groups of children (Table S7). Past studies have shown that immunoglobulin levels seem to recover simultaneously with B-cell reconstitution, where the recovery of Ig subclasses usually occurs in a unique order [23–24]. In this article, kids with CGD had higher C3 values than those with WAS at day 100 posttransplantation, and kids with CGD had higher C4 and IgA values than those with WAS at day 360 posttransplantation. However, kids with WAS had higher B-cell counts than those with CGD at days 100 and 180 posttransplantation, indicating that B-cell reconstitution levels were inconsistent with immunoglobulin recovery in children in the WAS and CGD groups. This may be because the number of B cells is not synchronized with the recovery of secretory function, but this speculation needs to be confirmed by further studies. Regarding IgG reconstitution, most kids in our center received regular gammaglobulin infusions during the first months posttransplantation, which may have led to similar levels of IgG reconstitution in the both groups of kids.
In the above analysis, it was demonstrated that the difference in age of transplantation had a relatively small effect on immune reconstitution in younger kids, whereas differences in graft type may have a partial effect on immune reconstitution in kids with WAS and CGD, and in addition, we speculate that it was associated with the fact that WAS and CGD are two different primary diseases. We also analyzed the posttransplantation infections in kids with WAS and CGD in different age groups (< 1 year, 1–3 years, 3–5 years, > 5 years) (Table S8), and results showed that among kids under 1 year old who underwent transplantation, the CGD group had a higher number of posttransplantation EBV infections and fungal infections compared to the WAS group. Among children 1–3 years old who underwent transplantation, the CGD group had a higher number of posttransplantation EBV infections and CMV infections than the WAS group. The number of posttransplantation fungal infections was also higher in the CGD group than in the WAS group among children over 5 years of age who received transplants. Delayed immune reconstitution may lead to an increased risk of infection-related death, which is a significant barrier to successful recovery from allo-HSCT [25]. Kids with WAS had fewer posttransplantation infections than kids with CGD, a fact that verifies that the lower incidence of posttransplantation fungal and viral infections in kids with WAS can be attributed to their better immune reconstitution.
Overall, this is the first comprehensive study on differences in immune reconstitution posttransplantation in patients with WAS and CGD. Our retrospective study has limitations regarding the irregularity, sample size, and patient follow-up time of immunosurveillance via flow cytometry or immunoturbidimetry after transplantation. These basic, real-world data can be extrapolated to other pediatric oncology transplant centers and form the basis for future collaborative studies. Interestingly, our findings suggest that immune reconstitution is faster in children with WAS than in children with CGD, and this difference may be related to the fact that the two diseases are different primary diseases and to graft types. In the future, we need to keep applying the existing standardized immune reconstitution monitoring methods and explore more patterns for immune reconstitution in children with different primary diseases undergoing allo-HSCT, which can guide physicians in using antimicrobial drugs and screening for pathogens and the development of strategies to enhance immune reconstitution, which will significantly improve the efficacy of allo-HSCT in children with immunodeficiency diseases.
During the immune reconstitution process, the WAS group had significantly higher lymphocyte subpopulation counts than the CGD group after transplantation, indicating that the rate of immunity recovery was faster in kids within the WAS group compared to those kids within the CGD group, which may be related to the type of graft (percentage undergoing UCBT) and the different primary diseases themselves.
During B-cell reconstitution in kids with WAS, kids who underwent non-UCBT had notably higher B-cell counts than kids who underwent UCBT at Days 15 and 30 posttransplantation, and kids who underwent UCBT had notably higher B-cell counts than kids who underwent non-UCBT at Days 100 and 180 posttransplantation, indicating that cord blood has strong B-cell reconstitution potential after allo-HSCT.
Funding
This study was supported by funds from the Chongqing Medical University Future Medical Youth Innovation Team Development Support Program (Grant No. W0132), the Chongqing Medical Scientific Research Project (Joint Project of Chongqing Health Commission and Science and Technology Bureau) (Grant No. 2021MSXM112), and the National Natural Science Foundation of China Youth Science Fund Project (Grant No. 81601753).
Competing Interests
The authors have no relevant financial or non-financial interests to disclose.
Author Contributions
All authors contributed to the study conception and design. Data collection were performed by Ya Zhou and Lanzhou Jia. Data analysis were performed by Ya Zhou. The first draft of the manuscript was written by Ya Zhou and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Data Availability
The datasets generated during and analysed during the current study are available from the corresponding author on reasonable request.
Ethics approval
The procedures followed in the study were approved by the Children’s Hospital of Chongqing Medical University Research Ethics Committee.
Consent to participate
Written informed consent was obtained from the parents.
Consent to publish
The authors affirm that the parents of the child research participants provided informed consent for publication of the images in Figures S1-S5 and the contents of Tables S1-S8.