PROLIFERATION OF RESTING LYMPHOCYTES IS INDUCED BY TRIGGERING T-CELLS THROUGH AN EPITOPE COMMON TO THE 3 CD18/CD11 LEUKOCYTE ADHESION MOLECULES

LFA-1, Mac-1, and p150,95 are a family of functionally important leucocyte integrins that share a common β-subunit and participate in cellular adhesion. Monoclonal antibody to LFA-1 were described to block T-cell-mediated killing by inhibiting adhesion to target cells and to decrease T cell responses by preventing cell-cell contact. Recently it was demonstrated that LFA-1 molecule was involved in signal transduction. We report here that a monoclonal antibody termed 6.7 reacting with the three members of the leucocyte integrins is able in the presence of monocytes to directly induce the proliferation of resting peripheral blood T cells obtained from normal individuals. These results suggest the possibility that LFA-1 molecules could trigger T lymphocyte activation in addition to their role in homing, growth, and differentiation. © 1991.