Patient Characteristics
The clinicopathological features of 79 LCH patients were summarized in Table 1. Among 79 childhood LCH patients, 43 (54.4%) were male, 36 (45.6%) were female. The median age at diagnosed was 4-year-old. As for HS classification, 47 (59.5%) were single-system involvement (SS), 14 (17.7%) were multi-systemic involvement without risk organ involvement (MS RO-), 18 (22.8%) were multi-system involvement with one or more risk organs involvement (MS RO+). Considering organ involvement, 5 (6.3%) presented with bone marrow involvement, 14 (17.7%) with liver involvement, 4 (5.1%) with spleen involvement, 9 (11.4%) with lung involvement and 30 (38%) with central nervous system (CNS) involvement. 23 (29.1%) patients presented with BRAF V600E mutation, while 5 (6.3%) presented with MAP2K1 mutation. Treatment efficacy was evaluated after 6-week induction therapy, 8 (10.1%) patients were non-active disease (NAD), 40 (50.6%) were active disease-better (AD-better), 12 (15.2%) were active disease-stable (AD-stable), while 19 (24.1%) were active disease-progressive (AD-progressive).
Changes of Peripheral Blood Lymphocyte Subsets After 6-week Induction Therapy
The changes in the proportion of peripheral blood lymphocyte subsets before and after 6-week induction therapy is shown in Figure 1 and Table 2. Results showed that the percentage of CD3+ T cells, CD3+CD4+ T cells and CD4/CD8 ratio were significantly increased after 6-week induction therapy (p<0.05), while the percentage of CD3+CD8+ T cells and B cells were significantly decreased after 6-week induction therapy (p<0.05). These results suggested that peripheral blood lymphocyte subsets could be influenced by induction therapy.
Correlation Between the Peripheral Blood Lymphocyte Subsets and Clinicopathological Features Before Induction Therapy
As shown in Figure 2, correlation analysis showed that CD3+CD8+ T cells and B cells before induction therapy were related to gender (r=-0.23 and 0.22). CD3+CD8+ T cells and CD4/CD8 ratio were related to age (r=0.28 and -0.32). CD3+ T cells, CD3+CD8+ T cells, NK cells, B cells and CD4/CD8 ratio were related to HS classification (r=-0.34, -0.23, 0.23, 0.24 and 0.27, respectively). As for risk organs involvement, CD3+ T cells, CD3+CD4+ T cells, CD3+CD8+ T cells, NK cells and B cells were related to liver involvement (r=-0.43,-0.29,-0.25,0.23 and 0.28, respectively), CD3+ T cells, CD3+CD8+ T cells, and B cells were related to bone marrow involvement (r=-0.36,-0.26 and 0.31, respectively), CD3+ T cells, CD3+CD8+ T cells, B cells and CD4/CD8 ratio were related to spleen involvement (r=-0.3,-0.36,0.33 and 0.25, respectively), CD4/CD8 ratio was related to lung involvement (r=0.27). CD3+CD8+ T cells and B cells were related to BRAF V600E mutation (r=-0.23 and 0.25), CD3+CD8+ T cells and B cells were also related to MAP2K1 mutation (r=-0.24 and 0.28).
The above results suggested that CD3+ T cells, CD3+CD4+ T cells, CD3+CD8+ T cells, NK cells and B cells at baseline might be indicators for liver involvement, CD3+ T cells, CD3+CD8+ T cells, and B cells may be predictors for bone marrow involvement, CD3+ T cells, CD3+CD8+ T cells, B cells and CD4/CD8 ratio may act as predictors for spleen involvement, while CD4/CD8 ratio could act as indicators for lung involvement. Moreover, CD3+CD8+ T cells and B cells might be closely related to BRAF V600E and MAP2K1 mutation.
Correlation Between the Changes of Peripheral Blood Lymphocyte Subsets and Clinicopathological Features After 6-week Induction Therapy
As shown in Figure 3 and Table 3, ∆CD3+ T cells, ∆CD3+CD4+ T cells, ∆CD3+CD8+ T cells, ∆NK cells and ∆B cells were related to treatment efficacy(p<0.05). As for organ involvements, ∆CD3+ T cells and ∆CD3+CD8+ T cells were related to liver involvement, ∆CD4/CD8 ratio was related to CNS involvement(p<0.05). Moreover, ∆CD3+ T cells and ∆B cells were related to BRAF V600E mutation, while ∆CD3+CD4+ T cells was related to MAP2K1 mutation (p<0.05). These results suggested that treatment efficacy, liver involvement, CNS involvement, BRAF V600E and MAP2K1 mutation might affect peripheral blood lymphocyte subsets after 6-week induction therapy.
Prognostic Factors
During follow-up, 34 patients presented with disease progression, the median PFS was 19 months, while 5 patients died, the median OS was 29 months. As shown in Table 4, HS classification, liver involvement, lung involvement, BRAF V600E and MAP2K1 mutation were predictive factors for PFS (p<0.05). Patients with SS disease, without liver and lung involvement, BRAF V600E and MAP2K1 wild type predicted superior PFS. Also, BRAF V600E and MAP2K1 wild type predicted superior OS (p<0.05).
Kaplan–Meier survival curves for PFS and OS with respect to ∆lymphocytes were shown in Figure 4-5 and Table5. As shown in Figure 4 and Table 5, increased ∆CD3+ T cells, decreased ∆CD3+CD4+ T cells, decreased ∆CD3+CD8+ T cells, decreased ∆NK cells and increased ∆B cells were predictors for superior PFS (p<0.05). As shown in Figure 5 and Table 5, increased ∆CD3+ T cells, decreased ∆CD3+CD8+ T cells and decreased ∆NK cells were predictors for superior OS (p<0.05).
Multivariate Cox regression analysis, including HS classification, liver involvement, lung involvement, BRAF V600E mutation, MAP2K1 mutation, ∆CD3+ T cells, ∆CD3+CD4+ T cells, ∆CD3+CD8+ T cells, ∆NK cells and ∆B cells, showed that ∆CD3+ T cells and ∆CD3+CD8+ T cells were independent prognostic factors for PFS (Table 6, p<0.05). However, multivariate Cox regression analysis including the above variables showed no independent predictors for OS.