CHARACTERIZATION OF A NEW HUMAN MACROPHAGE CELL-LINE 2MAC .1. EXPRESSION OF FUNCTIONAL MACROPHAGE CD16 (FC-GAMMA-RIIIA GAMMA) AND TISSUE FACTOR INDUCTION ON LIGATION OF HLA-DR/

A human macrophage-like line, designated SMAC, has been established fr om peripheral blood. 2MAC expresses a number of lineage-specific marke rs as well as a broad array of intercellular adhesion molecules. In pa rticular, 2MAC expresses CD16/Fc gamma RIII, the low-affinity Fc recep tor for IgG, as well as high levels of HLA class I and class II. Consi stent with this macrophage assignment, we present evidence that 2MAC e xpresses the macrophage form of CD16, namely, Fc gamma RIIIA/gamma. By several criteria also applicable to signal transducing NK CD16 and T cell CD3/TCR complexes, including modulation from the cell surface and Ca2+ mobilization in response to ligation by specific monoclonal anti body, CD16 expressed by SMAC is functional. Ligation of 2MAC HLA class II, but not HLA class I, by specific mAb induces an increase in free cytoplasmic Ca2+ concentration ([Ca2+](i)). This Ca2+ flux appears to be physiologically relevant, as ligation of HLA-DR, but not HLA class I, by mAb results in the efficient, Ca2+ mobilization-dependent induct ion of tissue factor by SMAC. 2MAC, therefore, should prove useful for studying signal transduction through macrophage CD16 and HLA class II . (C) 1997 Academic Press.