The activation of monocytes/macrophages by several stimuli is an initial event in the inflammatory response. To ascertain the importance of LTB(4) and 5-lypoxigenase in the inflammatory site, we isolated and stimulated rat adherent granuloma macrophages (RAGMs) with calcium ionophore in the presence or absence of regulated on activation, normal T expressed and secreted (RANTES) [CCL5] at different concentrations. We tested the hypothesis that RANTES may influence the production of LTB(4) stimulated by calcium ionophore A23187 (2.5 microM/ml) in rat adherent granuloma macrophages derived from granuloma induced by potassium permanganate diluted 1:40 saturated solution. To test this hypothesis, we measured LTB(4) production, in rat granuloma macrophages stimulated with A23187 (2.5 microM) alone and in combination with RANTES at different concentrations. In these studies, the cell-free supernatant of stimulated RAGMs with the ionophore A23187, resulted in a drastic increase of LTB(4). However, when the cells were treated with the combination RANTES plus A23187 the stimulatory effect was more pronounced than A23187 alone. LTB(4) production was quantitated. The calcium ionophore A23187 directly induced LTB(4) in macrophages, this production was markedly enhanced when the cells were pretreated with RANTES. However, the addition of RANTES in the absence of calcium ionophore A23187 did not directly induce LTB(4) release, nor was lypoxigenase expression augmented. Preincubation of RAGMs with NDGA (nordihydroguiaretic acid) (10(-5)M) completely abolished the production of LTB4 on RAGMSs challenged with A23187 in combination with RANTES or A23187 alone in the supernatants. Similar effects were obtained when the cells were pretreated with dexamethasone. These data suggest, for the first time, that RANTES may stimulate the release of LTB(4), only when it is associated to other stimuli and for this reason we conclude that RANTES modulates inflammatory diseases, and may require other stimuli to be effective in amplifying its spectrum of action(s).