Frontiers in Immunology (Sep 2021)

CD4+ T Cell Dependent B Cell Recovery and Function After Autologous Hematopoietic Stem Cell Transplantation

  • Clarissa Heck,
  • Sophie Steiner,
  • Eva M. Kaebisch,
  • Eva M. Kaebisch,
  • Marco Frentsch,
  • Friedrich Wittenbecher,
  • Friedrich Wittenbecher,
  • Carmen Scheibenbogen,
  • Carmen Scheibenbogen,
  • Leif G. Hanitsch,
  • Axel Nogai,
  • Philipp le Coutre,
  • Lars Bullinger,
  • Lars Bullinger,
  • Lars Bullinger,
  • Lars Bullinger,
  • Igor-Wolfgang Blau,
  • Il-Kang Na,
  • Il-Kang Na,
  • Il-Kang Na,
  • Il-Kang Na,
  • Il-Kang Na

DOI
https://doi.org/10.3389/fimmu.2021.736137
Journal volume & issue
Vol. 12

Abstract

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IntroductionHigh-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) represents a standard treatment regime for multiple myeloma (MM) patients. Common and potentially fatal side effects after auto-HSCT are infections due to a severely compromised immune system with hampered humoral and cellular immunity. This study delineates in depth the quantitative and functional B cell defects and investigates underlying extrinsic or intrinsic drivers.MethodsPeripheral blood of MM patients undergoing high-dose chemotherapy and auto-HSCT (before high-dose chemotherapy and in early reconstitution after HSCT) was studied. Absolute numbers and distribution of B cell subsets were analyzed ex vivo using flow cytometry. Additionally, B cell function was assessed with T cell dependent (TD) and T cell independent (TI) stimulation assays, analyzing proliferation and differentiation of B cells by flow cytometry and numbers of immunoglobulin secreting cells in ELISpots.ResultsQuantitative B cell defects including a shift in the B cell subset distribution occurred after auto-HSCT. Functionally, these patients showed an impaired TD as well as TI B cell immune response. Individual functional responses correlated with quantitative alterations of CD19+, CD4+, memory B cells and marginal zone-like B cells. The TD B cell function could be partially restored upon stimulation with CD40L/IL-21, successfully inducing B cell proliferation and differentiation into plasmablasts and immunoglobulin secreting cells.ConclusionQuantitative and functional B cell defects contribute to the compromised immune defense in MM patients undergoing auto-HSCT. Functional recovery upon TD stimulation and correlation with CD4+ T cell numbers, indicate these as extrinsic drivers of the functional B cell defect. Observed correlations of CD4+, CD19+, memory B and MZ-like B cell numbers with the B cell function suggest that these markers should be tested as potential biomarkers in prospective studies.

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