ELEVATED LEVELS OF T-CELL ACTIVATION ANTIGEN CD27 AND INCREASED INTERLEUKIN-4 PRODUCTION IN HUMAN LYMPHATIC FILARIASIS

To assess the immunological changes occurring during filarial infectio n with or without elephantiasis, 145 patients in different clinical gr oups from an endemic area in Indonesia were compared with respect to p lasma levels of both soluble CD25 (sCD25) and sCD27; interleukin-4 (IL -4) and interferon-gamma release by peripheral blood mononuclear cells was also measured in a smaller subset of individuals. Levels of sCD27 were significantly elevated in elephantiasis and microfilaremic patie nts compared with endemic normals (p < 0.002), whereas sCD25 levels re mained low in microfilaremics and was only slightly elevated in elepha ntiasis patients compared with endemic normals (p < 0.02). As activate d T cell populations release both sCD27 and sCD25, these findings impl y that there is filarial-driven activation of a T cell subset that rel eases sCD27 rather than sCD25. The expansion of a particular T cell po pulation by filarial parasites is further suggested by the enhancement in both IL-4-producing and CD4+CD27- T cells in PBMC from elephantias is and microfilaremic patients compared with endemic normals. More det ailed characterization and comparison of CD27- lymphocytes from these individuals may identify mechanisms involved in the pathogenesis of ly mphatic filariasis.