SUPPRESSIVE EFFECT OF INTERLEUKIN-4 NEUTRALIZATION DIFFERS FOR GRANULOMAS AROUND SCHISTOSOMA-MANSONI EGGS INJECTED INTO MICE COMPARED WITH THOSE AROUND EGGS LAID IN INFECTED MICE

The principal pathological manifestation of murine Schistosoma mansoni infection is the egg-induced granuloma. Synchronous pulmonary granulo mas forming around intravenously injected schistosome eggs are widely used to study the immunopathology of schistosomiasis. A number of anti cytokine antibody treatments have a remarkable effect in modulating gr anulomas in this model but little effect on the size of hepatic granul omas around laid eggs during experimental infection. To examine this d iscrepancy, ne examined the effects of anticytokine antibodies on live r and lung granulomas around injected eggs and around eggs laid during infection in both locations. Anti-interleukin-4 (IL-4) treatment grea tly reduced the volume of granulomas around eggs injected into the liv er via the portal vein and around eggs injected into the lung via the tail vein. On the contrary, granulomas around eggs laid by worms in ei ther the liver or the lung during the course of infection were not sig nificantly decreased in size by anti-IL-4 treatment. Thus, site is not important for the disparate effects of anti-IL-4 in granuloma formati on around injected versus laid eggs. This effect is seen in naive and sensitized animals and is most probably due to differences in the qual ity of injected eggs versus those laid in situ by the worms.