Effects of administration of anti-CD4 and anti-CD8 monoclonal antibodies on Mycobacterium paratuberculosis infection in intragastrically challenged mice.

In this study, we examined the roles of CD4+ and CD8+ cells in resistance to experimental paratuberculosis. Mice received purified anti-CD4 or anti-CD8 monoclonal antibodies before intragastric challenge with Mycobacterium paratuberculosis and on a biweekly basis for six months. This resulted in sustained depletion of CD4+ and CD8+ cells as verified by flow cytometry analysis of spleen cells from M. paratuberculosis infected mice. Depletion of CD4+ or CD8+ cells did not enhance fecal shedding of M. paratuberculosis, bacillary multiplication in the liver and ceca, nor histopathologic damage to the intestinal tract, mesenteric lymph nodes, spleen and liver. These data suggest that cells other than CD4+ or CD8+ cells are important for host defense in experimental paratuberculosis.