CD5 Antibodies Increase Intracellular Ionized Calcium Concentration in T Cells

摘要

The binding of a variety of monoclonal antibodies to the CD5 (T, gp67) pan T cell differentiation antigen has been shown to potentiate T cell proliferation. In this paper we show that CD5 monoclonal antibodies cause increased intracellular free calcium concentration ((Ca(2+))i) in T cells. An increase in (Ca(2+)i) occurred within 1 min in indo-1-loaded PBMC after the addition of CD5 monoclonal antibodies and cross-linking with a second step antimouse K light chain antibody. Cross-linking of CD5 was effective when done directly on the cell surface or by the administration of performed soluble complexes that contained CD5 antibodies. Calcium mobilization induced by suboptimal concentrations of CD5 antibodies was specifically augmented and sustained by CD5 antibodies, although the enhancement was modest in magnitude. Several CD5(+)/CD3- T cell leukemia lines failed to respond to CD5 stimulation, providing further evidence which indicates that the CD5 response depends on the cell surface expression of CD3 or a CD3-associated structure. These findings suggest that one mechanism for CD5-induced augmentation of mitogen-stimulated T cell proliferation involves increased (Ca(2+))i which is distinct from but interdependent with that induced by stimulation of the CD3 molecule. Keywords: Metabolism; Phorbol esters.