T-cell differentiation antigen cluster 2 (CD2) is a receptor for accessory cells and can generate and/or transduce accessory signals

Abstract

The role of CD2 antigen in T-cell activation was investigated using soluble-phase or crosslinked monoclonal anti-CD2 antibodies. Soluble-phase anti-CD2 inhibited T-cell activation when accessory signals were provided with accessory cells and not when 12- O-tetradecanoylphorbol -13-acetate provided the accessory signals to anti-CD3-treated T cells. Soluble-phase anti-CD2 also inhibited anti-CD3 and accessory cell-dependent increases in intracellular free calcium concentration. Crosslinked anti-CD2, on the other hand, mediated an increase in the concentration of intracellular free calcium in T cells. Crosslinked anti-CD2 also functioned as an accessory cell substitute in that it generated the required accessory signals and mediated significant proliferation of anti-CD3-treated T cells. Collectively, these findings support the concept that the CD2 antigen is a receptor for accessory cells and participates in accessory signal generation and/or transduction.