Deficits in the IgG(+) memory B‐cell recovery after anthracycline treatment is confined to the spleen of rhesus macaques

OBJECTIVES: Loss of vaccine‐induced antibodies (Abs) after chemotherapy against paediatric acute lymphoblastic leukaemia (ALL) is common and often necessitates re‐immunisation after cessation of treatment. Even so, some ALL survivors fail to mount or to maintain protective Abs. Germinal centres (GCs) are clusters of proliferating B cells in follicles of secondary lymphoid tissues (SLTs) formed during adaptive immune responses and the origins of long‐lived memory B and plasma cells that are the source of Abs. Furthermore, productive GC reactions depend on T follicular helper (T(FH)) cells. To understand why chemotherapy induces deficits in Ab responses, we examined how SLTs were affected by chemotherapy. METHODS: Rhesus macaques were infused with either three cycles of the anthracycline doxorubicin or saline, followed by immunisation with a de novo and booster antigen. Spleen and lymph nodes were removed, and memory B, bulk T and T(FH) cells were examined. RESULTS: Despite adequate GC morphology, a diminished memory and IgG(+) B‐cell population along with diminished total and booster vaccine‐specific IgG‐producing memory B cells were noted in the spleens of macaques with past doxorubicin exposure compared to the saline‐treated controls (P < 0.05). Intact bulk T and T(FH) cells were found in the SLTs of treated macaques, which displayed higher CD40L upregulation capacity by their splenic CXCR5(+) helper T cells (P < 0.01). In contrast to the spleen, the immune cell populations studied were comparable between the lymph nodes of both saline‐ and doxorubicin‐treated macaques. CONCLUSION: Our findings suggest that the splenic memory B‐cell subset, compared to its lymph node counterpart, is more severely altered by anthracycline treatment.