SECRETION OF TNF-α, IL-8 AND NITRIC OXIDE BY MACROPHAGES ACTIVATED WITH POLYANIONS, AND INVOLVEMENT OF INTERFERON-γ IN THE REGULATION OF CYTOKINE SECRETION

Abstract When macrophages derived from rat bone marrow were cultured in the presence of polyanions such as acetyl lignin (EP3), sulfonyl lignin (LS) or dextran sulfate (DS), the cells secreted TNF-α, IL-8 and nitric oxide (NO). EP3 had a dose-dependent effect on the secretion of TNF-α, IL-8 and NO. EP3 significantly affected secretion at concentrations greater than 5 μg/ml. The EP3 effect was at its maximum between concentrations of 50 and 100 μg/ml. LS and DS induced a slight increase in the secretion of cytokines and NO at a concentration of 100 μg/ml. The use of the reverse-transcription polymerase chain reaction (RT-PCR) showed that the increases in cytokine and NO secretion were due to an increase in cytokine mRNAs or NO synthase mRNA. Anti-TNF-α antibodies partially inhibited NO secretion by EP3-activated macrophages, although IL-8 secretion was independent of antibody treatment. The secretion of TNF-α and NO was also unaffected by the addition of anti-IL-8 antibodies. The addition of interferon-γ (IFN-γ) to the culture medium did not alter TNF-α and NO secretion by the EP3-activated macrophages, however, IL-8 secretion was increased when a low concentration of IFN-γ (0.2 U/ml) was added, but was reduced in the presence of a high concentration of IFN-γ (2000 U/ml). IFN-γ produced similar effects on cytokine and NO secretion in macrophages activated with lipopolysaccharide (LPS). Therefore, it is concluded that macrophages treated with polyanions secrete cytokines and NO, and that INF-γ is involved in the regulatory mechanism of cytokine and NO secretion.