HUMAN CHORIOCARCINOMA JAR CELLS CONSTITUTIVELY EXPRESS PRO-INTERLEUKIN-1-BETA THAT CAN BE RELEASED WITH FC-GAMMA RECEPTOR ENGAGEMENT

Some authors have suggested that fetally derived syncytiotrophoblasts, which form the barrier between mother and the fetus, are an integral part of a complex macrophage-cytokine network involving maternal leuko cytes, decidual cells, placental tissues, and even the fetus itself. W e report hen that syncytiotrophoblast-like JAR cells, a human chorioca rcinoma cell line, share another feature common to cells of the monocy te-macrophage lineage, the ability to secrete IL-1 beta when stimulate d through their Fc gamma receptors. We incubated JAR cells with physio logically relevant concentrations of model BSA-rabbit IgC-anti-BSA imm une complexes or monomeric rabbit IgG for periods of up to 72 h. Both monomeric IgG and immune complexes induced IL-1 beta from JAR cells, a lthough levels produced by immune complexes were approximately twice t hose induced by monomeric IgG. IL-1 beta secretion was not inhibited b y cycloheximide, and West ern blots of JAR cell lysates using pro-IL-1 beta MAb revealed constitutive expression of a 31-kD protein, whose l evels declined within 2 h of stimulation by either IgG or immune compl exes, but returned to baseline within 18 h.