Fc ϵRI and the T cell receptor for antigen activate similar signalling pathways in T cell-RBL cell hybrids

Abstract

In order to investigate the functional similarities of the high affinity receptor for IgE (Fc ϵRI) and the T cell receptor for antigen, we have developed a high efficiency polyethylene glycol-mediated fusion method to make somatic hybrids between cells from a mast cell line (RBL-2H3) and cells from T lymphoma cell lines (Jurkat and HPB-ALL). Using flow cytometry to select for the heterologously fused cells, we demonstrated that aggregation of the T cell receptor results in the efficient secretion of [ 3H]5-hydroxytryptamine from RBL cell-derived granules. In addition, both receptors mediate Ca 2+ mobilization in the hybrid cells that is insensitive to inhibition by the protein kinase C activator phorbol-12-myristoyl-13-acetate (PMA). In contrast, Ca 2+ mobilization caused by aggregation of Fc ϵRI in the parent RBL cells is completely inhibited by PMA. The results indicate that these two different receptors for foreign antigen can substitute for each other to trigger responses in the hybrid cells that are unique to each cell type. The methodology employed has general utility for studying signal transduction mediated by mammalian cell surface receptors.