A murine acquired immunodeficiency syndrome (MAIDS) is induced in genetically susceptible strains of mice inoculated with LP-BM5 murine leukemia virus. It is characterized by progressive lymphoproliferation, profound immunodeficiency, and the subsequent loss of resistance to opportunistic pathogens, including intestinal pathogens. Cellular and/or humoral immunity of gut-associated lymphoid tissues may play a key role in the elimination of these pathogens. We have previously demonstrated reductions in the number of mucosal T and B cells in MAIDS. In this study, the cytokine production by mesenteric lymph nodes (MLN) cells and their proliferative response to mitogens during MAIDS were investigated. Alterations were observed in the kinetics of MLN cell proliferation and cytokine secretion by in vitro mitogen-stimulated MLN cells during the retrovirus infection. Cytokine production was abnormally changed, with a gradual decrease in interleukin-2 (IL-2) production as well as an increase in IL-5 and IL-6 secretion. Interferon-gamma production was increased during the progression to MAIDS. The dysregulated release of cytokines by MLN cells due to retrovirus infection could lead to immune dysfunction. These data indicate that dysregulated cytokine secretion by MLN cells may be responsible for impaired mucosal immunity in AIDS, explaining the dramatic increase of opportunistic intestinal pathogens in individuals with AIDS.