Tespal Negatively Regulates BCR Signaling And B Cell Mediated Humoral Response

Tesapl is a newly identified adaptor protein which plays a vital role in T cell development and mast cell activation through regulation of TCR and Fc εRI signaling[1-2]. Despite highly similarity in both structure and function between TCR and BCR, how Tespal is involved in B cell response remains unknown. We analyzed the B cell components in Tespal-/-mice and found no difference in B cell development, activation or apoptosis from wildtype mice. However, we observed that, the absence of Tepsal enhanced B cell proliferation and Ca2+influx release as well as MAPK kinase activation and AKT phosphorylation upon BCR engagement. Moreover, Tespal-/-mice exerted stronger T cell dependent (TD) humoral response, rather than T cell independent (TI) response. We also found that Tespal deficiency led to higher incidence and accelerated severity in collagen induced arthritis. Thus, Tespal is crucial in the maintenance of normal function of B cells.