THYROTROPIN-RELEASING-HORMONE ENHANCES THE SUPEROXIDE ANION PRODUCTION OF RABBIT PERITONEAL-MACROPHAGES STIMULATED WITH N-FORMYL-METHIONYL-LEUCYL-PHENYLALANINE AND OPSONIZED ZYMOSAN

Effects of thyrotropin-releasing hormone (TRH) on the superoxide anion (O2-) production, which is essential for effective microbicidal and c ytotoxic activity in macrophages (Mphis), were investigated. TRH by it self failed to induce the O2-production of rabbit peritoneal Mphis eli cited with thioglycollate medium. However, Mphis preincubated with TRH showed the significant enhancements of O2- production following stimu lation with the chemotactic peptide, N-formyl-methionyl-leucyl-phenyla lanine (FMLP), at TRH concentrations from 10(-7), to 10(-4) M with a p eak enhancement at 10(-5) M. O2- generations of Mphis stimulated with opsonized zymosan (OZ) were also enhanced at TRH concentrations from 1 0(-10) to 10(-5) M with a peak enhancement at 10(-7) M. Maximal enhanc ements of O2- production were obtained with 10 min preincubation with TRH both for FMLP and OZ stimulations. TRH had no effect on O2- produc tion when stimulated with phorbol 12-myristate 13-acetate. Thyrotropin did not augment the O2 production induced with either FMLP or OZ. The se results indicate that TRH has the priming effect on FMLP- and OZ-in duced O2- production of rabbit peritoneal Mphis, although the mechanis m remains to be clarified.