2 Engagement of the monocyte antigen CD14 induces a state of IL-2 unresponsiveness in T cells

Abstract

CD14 is a 52 kD phosphatidylinositol-anchored protein expressed on mature monocytes. We have recently shown that engagement of CD14 by monoclonal antibodies (mAb) induces an increase in LFA-1/ICAM-1-dependent adhesiveness of the monocytes. We studied the role of CD14 in monocyte-T cell interaction by testing the effect of a panel of anti-CD14 mAbs on T cell proliferation.The proliferation of human T cells induced by antigens, mitogens, and anti-CD3 mAbs was inhibited by anti-CD14 mAbs, but not by isotype-matched control mAbs. Inhibition by anti-CD14 mAbs was epitope-dependent, and required physical contact between monocytes and T cells. CD14 engagement did not affect IL-2 receptor expression, nor IL-2 synthesis, but induced a state of unresponsiveness to IL-2. These data indicate that CD14 plays an important role in monocyte-T cell interactions.