ALTERATIONS OF THE MUCOSAL IMMUNE-SYSTEM DUE TO CRYPTOSPORIDIUM-PARVUM INFECTION IN NORMAL MICE

The mechanism with which the immune system of an immunocompetent host responds to Cryptosporidium parvum infection is still poorly understoo d. We have therefore investigated the immune response of adult immunoc ompetent C57BL/6 mice at Days 6 and 10 to postinfection during a self- limiting C. parvum infection We evaluated the immune changes at the le vels of intestinal intraepithelium and lamina propria as weal as mesen teric lymph nodes, At Day 6 postinfection, there was a decrease ha the production of IFN-gamma, IL-5, IL-6, and IL-10 by in vitro mitogen-st imulated intraepithelial lymphocytes. Moreover, an increase in the num ber of gamma delta-TCR(+), CD8(+), and cytoplasmic IgE(+) cells in int estinal lamina propria was found. Concomitantly, a significant decreas e in the number of cytoplasmic IgA(+) and IgG(+) cells was observed. T hese phenotypic changes may be associated with the cytokine-producing profile (decreased IL-4, IFN-gamma, and IL-10) by lamina propria lymph ocytes. At Days 6 and 10 postinfection cytoplasmic IgA(+) and IgG(+) c ell numbers remained. Nevertheless, the production of IL-5 and IL-10 b y intraepithelial lymphocytes was higher than the noninfected control values; these changes may be associated with the decreased CD4(+) cell numbers. in mesenteric lymphocytes IgG and IgA production in vitro wa s elevated while no changes were observed in cytokine production excep t for a significant decrease in HL-5. in conclusion, our results demon strate that an immunocompetent defense mechanism leading to a successf ul recovery from C. parvum infection involved changes of T-H1- or T-H2 -type cytokine production as well as alterations of time lymphocyte su bpopulation at mucosal-associated lymphoid tissues. (C) 1996 Academic Press, Inc.