Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/1996
Publication Date: N/A
Interpretive Summary: The protozoan parasite Cryptosporidia parvum is becoming increasingly important to the American beef and dairy industries. This importance is due to the fact that the organism can cause intestinal illness in a large range of hosts including cattle and humans. This results in production losses to the cattle industry and public concerns of environmental contamination from livestock raising practices. In cattle newborn calves are the animals affected, and this is assumed to be the result of their immature immune system. In this study we have shown that the intestine of newborn calves has very few mature immune cells. After infection with Cryptosporidia the number of mature cells greatly increases, and the mature cells are predominately one type. These results imply that if we could cause these mature cells to migrate into the gut at an earlier time after birth, the newborn animals may be more resistant to the parasites. Natural resistance would decrease production losses, and reduce environmental contamination attributed to the cattle industry.
Technical Abstract: Changes in intraepithelial (IEL), lamina propria (LPL) and draining lymph node (LNL) lymphocytes were assessed in 9-day-old calves during primary infection with Cryptosporidium parvum and in similarly aged non-infected calves. A very low percentage of both CD4+ and CD8+ T cells were found in IEL and LPL of non-infected calves. In infected compared to controls, percentages of CD2+, CD3+, CD4+, CD8+ T cells in IEL exhibited a significant increase (P<0.05), while the percentage of IL2R+ increased and the percentage of IgG+ cells decreased, but neither of these changes were statistically significant. In LPL, percentages of CD2+, CD3+, CD8+ and IL2R+ T cells were increased in infected compared to non- infected calves, while the percentage of IgG bearing cells decreased; but only the increase in CD3+, CD8+ and IL2R+ cells was significant (P<0.05). In LNL only minimal changes were seen, in fact the percentage of CD2+ T cells increased while the percentage of CD8+ T cells decreased; but neither of these differences was statistically significant. These findings indicate that T cell 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.