Human choriocarcinoma JAR cells constitutively express pro-interleukin- 1β that can be released with Fcγ 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 leukocytes, decidual cells, placental tissues, and even the fetus itself. We report that syncytiotrophoblast-like JAR cells, a human choriocarcinoma cell line, share another feature common to cells of the monocyte-macrophage lineage, the ability to secrete IL-1β when stimulated through the Fcγ receptors. We incubated JAR cells with physiologically relevant concentrations of model BSA-rabbit IgG-anti-BSA immune complexes or monomeric rabbit IgG for periods of up to 72 h. Both monomeric IgG and immune complexes induced IL-1β from JAR cells, although levels produced by immune complexes were approximately twice those induced by monomeric IgG IL-1β secretion was not inhibited by cycloheximide, and Western blots of JAR cell lysates using pro-IL-1β MAb revealed constitutive expression of a 31-kD protein, whose levels declined within 2 h of stimulation by either IgG or immune complexes, but returned to baseline within 18 h.