Cytokine detection at the site of l.(l.) Amazonensis subcutaneous inoculation in mice depleted of Natural Killer cells

Abstract

BALBI c mice depleted and non-depleted of Natural Killer (NK) cells were infected subcutaneously with 10⁷ stationary phase promastigotes of Leishmania (Leishmania) amazonensis and samples were taken at 24 hours and 7 days after infection. In NK cell-depleted mice, the NK cytotoxic activity of spleen cells decreased at 7 days after infection and more parasites were found in the lesion. The NK cell populations were analyzed by immunohistochemistry in spleen cryosections. An increase of NK1.1⁺ expression and a decrease of NK5E6⁺ antigen expression was observed in NK cell-depleted mice compared to non-depleted mice. When the presence of IFN-g, IL-12 and IL-4 at the site of parasite inoculation was analyzed by immunohistochemistry, a large amount of cytokines was detected in K cell-depleted mice at 24 hours and 7 days after infection. In non-depleted mice, there was a small amount of IL-12 at 24 hours and of IL-4 at 7 days after infection. These data cells suggest that K cell depletion by 90Srresults in increased parasitism in the lesion. The increase of NK1.1⁺ expression, which mainly produces IL-4, may take part in the progression of the infection.