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.