Mast cell 2B4 induces antigen-specific CD8+ T cells function (IRC4P.457)

Abstract The signaling lymphocyte activation molecule (SLAM) family receptor, 2B4 (CD244), is expressed on NK cells, a subpopulation of T cells (including CD8+ T cells and γ/δ T cells), monocytes/macrophages, basophils, eosinophils, and mast cells (MCs). Although 2B4 is known to play an important role in the biological function of NK cells, the role of 2B4 on MCs remains unclear. Here, we identified a critical role for 2B4 on MCs in antigen-specific CD8+ T cell activation. Using a co-culture system, we demonstrated that OT-I CD8+ T cells acquired higher expression of CD69 and CD25 activation markers in the presence of OVA-pulsed wild type (WT) bone marrow-derived MCs (BMMCs) but not 2B4 KO BMMCs. In addition, CD8+ T cell activation was significantly reduced by incubation with 2B4-blocked MCs. This effect was potentiated by incubation with CD48-blocked MCs, indicating that while 2B4/CD48 interactions influenced CD8+ T cell activation, CD2/CD48 interactions were also involved in MC regulation of CD8+ T cells. Moreover, CD8+ T cell proliferation was enhanced by 2B4-expressing MCs. Thus, this study provides insight on how MCs can influence CD8+ T cells via 2B4/CD48 interactions.