Differential effect of interferon expression of IgG- and IgM-Fc receptors on human lymphocytes.

Mononuclear cells from the blood of healthy normal humans were kept in culture under nonstimulating conditions for 48 hr in the presence or absence of human leukocyte and fibroblast interferons. The number of cells bearing IgM-Fc and IgG-Fc receptors on the cultured cells was determined by rosette formation with ox red blood cells coated with IgM and IgG antibodies. Both interferons suppressed the expression of IgM-Fc receptors on the cells in culture and, conversely, augmented that of IgG-Fc receptors. The suppressed expression of IgM-Fc receptors and enhanced expression of IgG-Fc receptors occurred in parallel within 1 hr after incubation and reached a maximum at 6 hr. Expression of both receptors returned to normal levels after overnight cultivation, although the enhanced expression of IgG-Fc receptors persisted for a longer time than did the suppressed expression of IgM-Fc receptors. Treatment of leukocyte interferon with heat (at 56 °C for 1 hr) and acid (pH 2.0) did not abolish these activities. The effects were found to be dose-dependent and blocked by 10-9 M ouabain. Pretreatment of lymphocytes with interferon for 3 hr was found to be as effective as having interferon present during the entire culture period. The enhanced expression of IgG-Fc receptors was observed on T- and non-T-enriched lymphocyte populations, and the suppressed expression of IgM-Fc receptors was also observed on T-enriched populations. The dose of interferon needed to induce these modulations of Fc receptors could also augment the natural cytotoxicity to human lymphoid (BJAB) cells and ADCC to chicken red blood cells by peripheral blood lymphocytes.