GAMMA-INTERFERON IN APLASTIC-ANEMIA - INABILITY TO DETECT SIGNIFICANT LEVELS IN SERA OR DEMONSTRATE HEMATOPOIETIC SUPPRESSING ACTIVITY

Abstract

A radioimmunoassay (RIA) was used to quantitate biologically active gamma interferon (INF-.gamma.) in sera and in supernatants of cultured mononuclear cells obtained from 50 patients with aplastic anemia. Only five of the 50 serum samples had INF-.gamma. levels above background (> 0 < 0.5 units per mL). Detectable levels of spontaneous INF-.gamma. (0.3 to 868 U/mL) were found in 18 of the 50 mononuclear cell supernatants tested. The addition of patient sera or INF-.gamma. positive supernatants to cultures of normal hematopoietic colonies did not result in reduced colony growth. Flow cytofluorimetric analysis of mononuclear cells failed to establish a correlation between the presence of INF-.gamma. in supernatants and the number of activated T cells or natural killer (NK) cells in the monounclear cell population. However, a singificant correlation did exist between the presence of monocytes and the production of INF-.gamma.. Contrary to previous reports, our data suggest that patients with aplastic anemia do not have high circulating levels of INF-.gamma.. Unstimulated mononuclear cells from some patients will produce significant levels of INF-.gamma., but this does not result in decreased in vitro hematopoiesis.