Conclusions
This pilot study demonstrates that immune recovery can be measured using CD4+ T-cell counts, in vitro antigen stimulation and selected cytokines (IFNγ, IL-1β, IL-4, IL-6, IL-17, IL-21, IL-31) in alloHSCT recipients. While larger studies are required, monitoring immune recovery may have utility in predicting infection risk post-alloHSCT.
Methods
Twenty, 13, 11, 9 and 9 alloHSCT recipients had blood collected at baseline (time of conditioning) and 3-, 6-, 9-, and 12-months post-alloHSCT, respectively. Clinical data were collected, and immune recovery was measured using immunophenotyping, lymphocyte proliferation, cytokine analysis and antibody isotyping.
Results
Median absolute T- and B-cell counts were below normal from baseline until 9- to 12-months post-alloHSCT. Median absolute CD4+ T-cell counts recovered at 12-months post-alloHSCT. Positive proliferative responses to Aspergillus, cytomegalovirus (CMV), Epstein-Barr virus (EBV), influenza and tetanus antigens were detected from 9 months. IL-6 was the most abundant cytokine in cell cultures. In cultures stimulated with CMV, EBV, influenza and tetanus peptides, the CD4+ T-cell count correlated with IL-1β (P = 0.045) and CD8+ T-cell count with IFNγ (P = 0.013) and IL-1β (P = 0.012). The NK-cell count correlated with IL-1β (P = 0.02) and IL-17a (P = 0.03). Median serum levels of IgG1, IgG2 and IgG3 were normal while IgG4 and IgA were below normal range throughout follow-up. Conclusions: This pilot study demonstrates that immune recovery can be measured using CD4+ T-cell counts, in vitro antigen stimulation and selected cytokines (IFNγ, IL-1β, IL-4, IL-6, IL-17, IL-21, IL-31) in alloHSCT recipients. While larger studies are required, monitoring immune recovery may have utility in predicting infection risk post-alloHSCT.