CD19+CD5+ B Cells and B1-Like Cells Following Allogeneic Hematopoietic Stem Cell Transplantation

We and others have previously reported the expansion of CD5(+)CD19(+) B cells after allogeneic hematopoietic stem cell transplantation. Recently, the equivalent of B1 cells in mice has been described in humans as CD20(+)CD27(+)CD43(+)CD70(-) B cells. In this article, we report that although 39% of CD5(+)CD19(+) cells were CD43(+) in controls, >75% of CD5(+)CD19(+) cells were CD43(+) in patients independent of the presence or absence of chronic graft-versus-host disease (GVHD) (P = .0001). CD5(+)CD19(+) B cell, CD5(+)CD43(+)CD19(+) B cell, and CD27(+)CD43(+) B cell counts were significantly lower in the patients with previous chronic GVHD, and this effect of GVHD was similar in both CD5(+) and CD5(-) within the CD27(+)CD43(+) B cell subset. Our results strongly suggest that the previously reported expansion of the CD5(+)CD19(+) population might be related to an expansion of the CD27(+)CD43(+) B cell subset and that CD27(+)CD43(+) B cell reconstitution is impaired in patients with chronic GVHD. (C) 2013 American Society for Blood and Marrow Transplantation.