Studies on intraepithelial lymphocytes and cytokine production in the protection against nematode infection

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The mechanism of worm expulsion, spontaneous cure, of the intestinalnematodes is recently understood that the direct effector cells against parasites are selective among various intestinal nematode species. To generalize the mechanism of worm expulsion, we need to understand the mechanism for regulating direct effector cells. We focused on intestinalintraepithelial cells (IEL), and tried to study on T cell subsets and cytokine production in S.ratti (Sr) and N.brasiliensis (Nb) -infection by flow cytometry and RT-PCR.We examined also on mesenteric lymph node cells by those methods. Mean recovery of IEL from Sr-infected and Nb-infected mice were less than 40% and 6% of IEL from normal mice, respectively. Percentage of CD3^+, CD4^+, CD8^+ and gammadeltaTCR^+ cells was not different basically between IEL from Sr-infected and that from Nb-infected mice. Th2 type cytokines, IL-4 and IL-3 mRNA were detected clearly in IEL from Sr-infected mice on day 7 but not in normal IEL.Th1 type cytokine, … More IFN-gamma mRNA was detected in normal IEL and hardly changed in the infection. IEL probably play a role on the expulsion of Sr, because IL-3 mRNA,a mast cell growth factor messenger, was increased in IEL in the infection. We could not examine the expression of mRNA in IEL from Nb-infected mice.Intracellularcytokines in mesenteric lymph node cells were detected by flow cytometry. IL-3 containing cells increased in the mesenteric lymph node both in Sr-and Nb-infection. IL-4 or IFN-gamma containing cells were not different basicallyamong infection with the two parasites. TNF containing cells, however, were clearly different between Sr-and Nb-infection. Percentage of TNF containing cells decreased in Sr-infection but not in Nb-infection.These results may be helpful to clarify the selective mechanism among different intestinal nematode species. We also examined mechanism of regulating mucus secretion in Nb-infected mice, because less IEL were recovered and more mucus seemed to be secreted in Nb-infection. We found that mucus secretion from goblet cells may be regulated by CD4^+ cells. Less