ELEVATED INTERLEUKIN-10-TO-INTERLEUKIN-12 RATIO IN FELINE IMMUNODEFICIENCY VIRUS-INFECTED CATS PREDICTS LOSS OF TYPE-1 IMMUNITY TO TOXOPLASMA-GONDII

Similar to human immunodeficiency virus, feline immunodeficiency virus (FIV) induces immunodeficiency and enhanced susceptibility to seconda ry pathogens. To explore cytokine alterations in lentivirus immunodefi ciency, constitutive mRNA expression was measured in lymph nodes of he althy and FIV-infected cats before and after challenge with Toxoplasma gondii. Cytokine mRNA expression was similar in control and FIV-infec ted cats during the first 10 weeks after infection. At 16 weeks, inter feron (IFN)-gamma, tumor necrosis factor-alpha, and interleukin (IL)-1 0 mRNA were increased in FIV-infected cats. Challenge with T.gondii in duced an increase in IL-2, IFN-gamma, and IL-12 in the lymph nodes of control cats, whereas IFN-gamma and IL-10 but not IL-2 or IL-12 increa sed in the lymph nodes of FIV-T, gondii coinfected cats. These results indicate that FIV immunodeficiency may derive from a failure to gener ate an IL-12-dependent type 1 response and that an elevated level of I L-10 mRNA expression is a predictor of lentivirus immunodeficiency.