LYMPHOCYTE DYNAMIC PATTERNS IN CATTLE DURING A PRIMARY INFECTION WITHCRYPTOSPORIDIUM-PARVUM

Changes in intraepithelial (TEL), lamina propria (LPL), and draining l ymph node (LNL) lymphocytes were assessed in 9-day-old calves during p rimary infection with Cryptosporidium parvum and in similarly aged non infected calves. A very low percentage of both CD4+ and CD8+ T cells w ere found in IEL and LPL of noninfected calves. In infected compared t o controls, percentages of CD2+, CD3+, CD4+, and CD8+ T cells in IEL e xhibited a significant increase (P < 0.05), whereas the percentage of IL2R+ increased and the percentage of IgG+ cells decreased, but neithe r of these changes were statistically significant. In LPL, percentages of CD2+, CD3+, CD8+, and IL2R+ T cells were increased in infected com pared to noninfected calves, whereas the percentage of IgG-bearing cel ls decreased; but only the increase in CD3+, CD8+, and lL2R+ cells was significant (P less than or equal to 0.05). In LNL only minimal chang es were seen. In fact, the percentage of CD2+ T cells increased wherea s the percentage of CD8+ T cells decreased, but neither of these diffe rences was statistically significant. These findings indicate that T c ell subsets in the ileal mucosa of naive neonatal calves are different than those of adult cattle, and that the immune response to C. parvum infection differs in ileal mucosa when compared to the regional lymph nodes.