RhoH is required to maintain the integrin LFA-1 in a nonadhesive state on lymphocytes.

Lymphocyte function-associated antigen 1 (LFA-1) is relatively nonadhesive on resting lymphocytes; however, the mechanisms underlying changes in its adhesiveness are poorly understood. In this study, we generated a Jurkat T cell clone, J+hi1.14, that contained low amounts of mRNA for RhoH, a leukocyte-specific inhibitory Rho family member. J+hi1.14 cells expressed constitutively adhesive LFA-1 and the cells bound spontaneously to intracellular adhesion molecules 1, 2 and 3. Reconstitution of RhoH mRNA expression in J+hi1.14 cells reverted the adhesion phenotype to that of wild-type. We obtained similar results using RNA interference in peripheral blood lymphocytes. These data demonstrate that RhoH is required for maintenance of lymphocyte LFA-1 in a nonadhesive state.