GRANULOMA CYTOKINES IN MURINE CYSTICERCOSIS

Neurocysticercosis, caused by Taenia solium, is one of the most common causes of seizures worldwide. The symptoms result from granulomatous inflammation associated with dying cyst forms of the parasite. Althoug h the invasive larvae can be killed by immune serum plus complement, i mmunity to the cyst stage depends on a cellular response. This dichoto mous immune response is reminiscent of the extremes of the immune resp onse associated with T helper 1 (Th1) and Th2 cytokine profiles. To ch aracterize the cytokine response in cysticercosis, granulomas were rem oved from the peritoneal cavity of mice infected with Taenia crassicep s cysts and examined for cytokine message by in situ hybridization usi ng S-35-labeled RNA probes. The granulomas were staged based on histol ogic appearance of the degenerating parasite. Message for gamma interf eron (IFN-gamma) was identified by light microscopy in 11 of the 12 gr anulomas, and interleukin-2 (IL-2) message was identified in 9 of the 12. By laser scanning confocal microscopy, significantly increased IFN -gamma and IL-2 pixel intensity was identified in nearly all of the gr anulomas from early histologic stages. Message for IL-4 was seen in 6 of the 12 granulomas. Only granulomas with complete destruction of the parasite architecture displayed more than minimal amounts of IL-4 mes sage by light microscopy, and only 2 of 12 granulomas had IL-4 pixel i ntensity significantly above background. Only minimal amounts of IL-10 message were detected in 4 of 11 granulomas. Thus, early granulomas i n cysticercosis are predominantly associated with a Th1 response, wher eas later granulomas, in which parasite destruction is complete, have a mixture of Th1 and IL-4. The Th1 response appears to play an importa nt role both in the pathogenesis of disease as well as in the clearing of the parasites, with IL-4 involved in downregulation of the initial response.