INTERLEUKIN-LO DOWN-REGULATES PROTECTIVE IMMUNITY TO BRUCELLA-ABORTUS

In vivo neutralization of interleukin-10 (IC-10) with an anti-IL-10 mo noclonal antibody resulted in up to 10-fold fewer bacteria in the sple ens of BALB/c mice infected with the virulent Brucella abortus strain 2308. In vitro neutralization of endogenous IL-10 in brucella antigen- stimulated cultures of splenocytes from infected mice resulted in incr eased gamma interferon production in these cultures, whereas exogenous recombinant IL-10 inhibited the ability of peptone-elicited peritonea l macrophages to control intracellular brucellae. These data suggest t hat IL-10 may be downregulating the immune response to B. abortus by a ffecting both macrophage effector function and the production of the p rotective Th1 cytokine gamma interferon.