Reversible expression of CD138 on mature follicular B cells is downregulated by IL-4

Abstract

CD138, known as a marker of plasma cells, was reported to be expressed to an intermediate level in the murine bone marrow precursor B cells. Here an intermediate level of CD138 expression was also noted in a subpopulation of splenic follicular B cells, which were distinguishable from CD138(high) plasma cells, whereas the majority of transitional or marginal zone B cells did not express CD138. These CD138(int) B cells were IgM(low)IgD(high) mature B cells, located within follicular B cell zone, and expressed a lower level of CD21 than CD138(-) follicular B cells. During in vitro culture of splenic cells, the proportion of CD138(int) B cells increased, which was noticeably reversed by the addition of IL-4 to the culture. The experiments with sorted CD138(int) cells showed that IL-4-mediated regulation of the CD138 expression was B cell-intrinsic and independent of in vitro B cell death. Our results demonstrate that mouse CD138(int) B cells characterize a subpopulation of IgM(low)IgD(high) mature follicular B cells. The CD138 expression on follicular B cells may represent a reversible status, reflecting a dynamic state probably influenced by IL-4.

Keywords: CD138; FO B cells; Follicular B cell; IL-4; MZ B cells; NKT cells; PNA; STAT6; Syndecan-1; T helper type 2 cells; Th2 cells; follicular B cells; interleukin-4; marginal zone B cells; natural killer T cells; peanut agglutinin; signal transducer and activator of transcription 6.