Analysis of granzyme B activity as a surrogate marker of Leishmania-specific cell-mediated cytotoxicity in zoonotic cutaneous leishmaniasis.

The purpose of this study was to analyze Leishmania-specific cell-mediated cytotoxicity in individuals with active or healed zoonotic cutaneous leishmaniasis (ZCL). The (51)Cr-release assay revealed a significant cytotoxicity against L. major-infected autologous macrophages in individuals with active or healed ZCL. As a surrogate marker of cytotoxic response, a test based on the measure of granzyme B activity in parasite-stimulated peripheral blood mononuclear cells was optimized and evaluated in 88 individuals. Increased granzyme B activity was found in 62.5% of patients with active ZCL and in only 30% of individuals with healed ZCL. In both groups, granzyme B activity was significantly higher than in healthy, leishmanin skin test-negative control subjects (P<.05). These data provide additional evidence that Leishmania-specific cell-mediated cytotoxicity is part of the acquired immune response developed against the parasite. Its role in resistance to reinfection should be evaluated.