Differential Regulation of IgA+ B Cells in Vitro by Stromal Cells from Distinctive Anatomical Compartments

B cell development is regulated by stromal cells that form a supportive microenvironment. Bone marrow (BM), spleen (Sp), and the gut lamina propria (LP) constitute distinct anatomical compartments that support B cell differentiation. In order to examine the effect of stromal cells on IgA+ B cells, I developed an in vitro system to co-culture gut LP, BM, or Sp-derived stromal cells with B cell progenitors to characterize the signals to generate IgA+ B cells. In this study, I characterized optimal conditions for the in vitro generation of IgA+ B cells. I found that gut LP stromal cells promote IgA+ B cell accumulation through producing soluble stimulatory factors. In contrast, BM and Sp stromal cells impaired IgA+ B cell accumulation in vitro by inhibiting proliferation and differentiation of IgA+ B cells. These observations provide new insights into how stromal cells from different anatomical locations shape IgA+ B cell responses.M.Sc