Vasorin Expression During Mouse B cell Development (138.31)

Abstract

Abstract The stages of B cell development are delineated by stage-specific timing of gene and cell surface marker expression coinciding with exposure to cytokines and growth factors. Transforming growth factor beta (TGF-β) has been previously shown to affect lymphopoesis, as well as more mature processes, such as B-cell isotype switching. Receptors for TGF-β are diverse and widely distributed but display some tissue specificity. Here we describe expression of a Type-I TGF-β membrane receptor, vasorin, previously reported to be almost exclusively expressed by vascular tissue. Using RT-PCR analysis, the message for vasorin was identified in mouse pre-B cell lines prior to BCR gene rearrangement. Thus, vasorin expression may be closely linked to early lymphocyte development at the pro and pre-B stages. To verify that this finding was not an artifact of the cell lines, we looked for vasorin message in primary cell suspensions of spleen, thymus and liver from neonatal mice. Vasorin gene expression is readily detected in the primary repositories of B cell development, the spleen and liver, but not in primary thymocytes. These data suggest that receptor binding of TGF-β may be more vital to B-cell than to T-cell development. Vasorin expression by progenitor B cells may ensure measured proliferation via TGF-β receptor signaling.