The effect of interleukin-4 on the macrophage respiratory burst is species dependent

Preexposure of human monocytes to recombinant human interleukin-4 (IL-4) suppressed the respiratory burst response to a number of different stimuli, including phorbol myristate acetate, zymosan, platelet-activating factor and the chemotactic peptide, f-met-leu-phe. Under similar conditions, the respiratory burst of murine macrophages was enhanced by preexposure to recombinant murine IL-4. By conducting our studies on cells from different species under similar conditions we have demonstrated that there is a significant disparity in the effects of IL-4 on human and murine macrophages thus providing an explanation for some apparent inconsistencies in the literature and highlighting the need for caution when extrapolating data across species barriers.