Superoxide (O2 −) generation of guinea-pig macrophages induced by wheat germ agglutinin (WGA) was suppressed to a great extent by the inhibition of transmethylation with 3′-deazaadenosine. When macrophages were stimulated with phorbor myristate (PMA) instead of WGA, the suppression of O2 − generation of macrophages was observed to be slight despite the presence of 3′-deazaadenosine. These results were confirmed under various conditions. Thus the WGA-stimulated O2 − generation of macrophages is probably associated with transmethylation, but the PMA-stimulated O2 − generation is not. WGA-stimulated O2 − generation of macrophages was also inhibited in the presence of dibutyryl cAMP or prostaglandin E2 (PGE2), substances that increase intracellular cAMP, but PMA-stimulated O2 − generation was only slightly affected by these compounds. These results suggest that the mechanism for O2 − generation of macrophages caused by WGA is different from that for O2 − generation caused by PMA.
