RESUMO
Cultured splenic mononuclear adherent cells (SMAc) from normal BALB/c mice as well as those from mice bearing 10-day sarcoma 180 (S180), exhibited a marked increase in Escherichia coli lipopolysaccharide-stimulated interleukin-1 (IL-1) production, when compared to spontaneous values. On days 20 and 30 following S180 challenge, a decrease in this effect on IL-1 production in treated and untreated SMAc was observed. Concomitantly with the alterations in the regulation of IL-1 production during tumor growth, an increase in the levels of prostaglandin E2 and serum immune complexes could be detected. These data suggest that the immunosuppression associated with later stages of tumor development may be due to direct effects on monocytes, by means of a down-regulation of IL-1 production.