EFFECT OF INTERLEUKIN-4 ON ALLERGEN-INDUCED ARACHIDONIC-ACID METABOLISM OF RAT PERITONEAL-MACROPHAGES DURING IMMEDIATE HYPERSENSITIVITY REACTIONS

The aim of this study was to investigate the [H-3]arachidonic acid met abolism of rat peritoneal macrophages, induced by allergen (ovalbumin) and the impact of interleukin-4 on this process, We established that ovalbumin induces an increase of [H-3]arachidonic acid mobilisation fr om membrane lipids and of [H-3]arachidonic acid catabolism, principall y by the 5-lipoxygenase pathway, when the macrophages are sensitized a nd when serum is present. The allergen effect is not modified by the p resence of interleukin-4 in the culture medium of macrophages 15 h bef ore the allergen challenge. We also showed that, whereas the basal [H- 3]arachidonic acid metabolism of macrophages from control and actively sensitized rats is not different, interleukin-4 increases the [H-3]ar achidonic acid mobilisation and catabolism by cyclooxygenase and 5-lip oxygenase pathways in macrophages from control rats although it does n ot in macrophages from actively sensitized rats. In macrophages from c ontrol rats, the interleukin-4 effect is diminished by the addition of IgEs to their culture medium. In summary, interleukin-4 has an enhanc er effect on the macrophage arachidonic acid catabolism that depends o n the sensitization condition of the cell but that has no consequences on the further increased arachidonic acid metabolism induced by the a llergen. (C) 1997 Elsevier Science B.V.