Sequential monitoring of lymphocyte subsets and of T-and-B cell neogenesis indexes to identify time-varying immunologic profiles in relation to graft-versus-host disease and relapse after allogeneic stem cell transplantation

Abstract

T and B lymphocyte subsets have been not univocally associated to Graft-versus-host disease (GVHD) and relapse of hematological malignancies after stem cell transplantation (SCT). Their sequential assessment together with B and T cell neogenesis indexes has been not thoroughly analysed in relation to these changing and interrelated immunologic/clinic events yet.Lymphocyte subsets in peripheral blood (PB) and B and T cell neogenesis indexes were analysed together at different time points in a prospective study of 50 patients. Principal component analysis (PCA) was used as first step of multivariate analysis to address issues related to a high number of variables versus a relatively low number of patients. Multivariate analysis was completed by Fine-Gray proportional hazard regression model. PCA identified 3 clusters of variables (PC1-3), which correlated with acute GVHD: PC1 (pre-SCT: KRECs≥6608/ml, unswitched memory B <2.4%, CD4+TCM cells <45%; HR 0.5, p = 0.001); PC2 (at aGVHD onset: CD4+>44%, CD8+TCM cells>4%; HR 1.9, p = 0.01), and PC3 (at aGVHD onset: CD4+TEMRA<1, total Treg<4, TregEM <2 cells/μl; HR 0.5, p = 0.002). Chronic GVHD was associated with one PC (TregEM <2 cells/μl at day+28, CD8+TEMRA<43% at day+90, immature B cells<6 cells/μl and KRECs<11710/ml at day+180; HR 0.4, P = 0.001). Two PC correlated with relapse: PC1 (pre-SCT: CD4+ <269, CD4+TCM <120, total Treg <18, TregCM <8 cells/μl; HR 4.0, p = 0.02); PC2 (pre-SCT mature CD19+ >69%, switched memory CD19+ = 0 cells and KRECs<6614/ml at +90; HR 0.1, p = 0.008). All these immunologic parameters were independent indicators of chronic GVHD and relapse, also considering the possible effect of previous steroid-therapy for acute GVHD. Specific time-varying immunologic profiles were associated to GVHD and relapse. Pre-SCT host immune-microenvironment and changes of B cell homeostasis could influence GVH- and Graft-versus-Tumor reactions. The paradoxical increase of EM Treg in PB of patients with GVHD could be explained by their compartmentalization outside lymphoid tissues, which are of critical relevance for regulation of GVH reactions.

A prospective observational study of immune reconstitution following transplantation with post‐transplant reduced‐dose cyclophosphamide from HLA ‐haploidentical donors

“…In contrast, at the late evaluation point (day 90), close to the onset of chronic GVHD, increased CD8+ effector memory T‐cell counts were associated with the risk of chronic GVHD. This result is concordant with previous reports showing that memory T cells principally contribute to the dysregulated and skewed immune system in chronic GVHD . There is a report that the naïve T‐cell population increased at 3 months after HCT in patients with chronic GVHD .…”

“…Another possible reason may be the inconsistent and complicated interaction among many immunological indicators during reconstitution. We, therefore, collectively evaluated lymphocyte subsets and applied PCA to reduce the noise due to interaction among variables .…”

“…In the analysis of the effect of immunological variables on chronic GVHD for the entire cohort, principal component analysis (PCA) was applied as the first step of the multivariate analysis to compensate for the limit and to address issues related to the large number of variables in the lymphocyte subsets and the low number of patients . The details of PCA are described in the Appendix S1.…”

Early CD8+-recovery independently predicts low probability of disease relapse but also associates with severe GVHD after allogeneic HSCT

“…Kim et al found that low ALC in the first three months after transplantation is a significant predictive factor of poor OS and higher NRM [ 10 ]. The correlation of early lymphocyte reconstitution and early recovery of lymphocyte function with improved transplant outcomes has been corroborated also in the other previous studies [ 27 – 29 ]. Furthermore, an early rise in the ALC and absolute monocyte count has also been reported to be associated with significantly better OS in the context of PBSC, BM, and cord blood derived grafts [ 30 ].…”

Extracorporeal Photopheresis (ECP) and the Potential of Novel Biomarkers in Optimizing Management of Acute and Chronic Graft vs. Host Disease (GvHD)

“…Conversely, CEC counts returned to pre-transplant baseline after treatment response. Another method is detailed monitoring and statistical analyses of multiple subsets of lymphocytes by flow cytometry; in a study of 50 HSCT patients aGvHD development was significantly associated with increased frequencies of central memory CD4 T cells (Tcm) and memory B-cells pre-HSCT and by increased frequencies of memory, naïve, T-reg and recent thymic emigrant (RTE) T-cell subsets at aGVHD onset (37).…”