ANALYSIS OF T-CELL POPULATIONS AND IL-3 MESSENGER-RNA EXPRESSION IN MESENTERIC LYMPH-NODE CELLS AND INTESTINAL INTRAEPITHELIAL LYMPHOCYTES IN STRONGYLOIDES RATTI-INFECTED MICE

T cell populations and IL-3 mRNA expression were analysed in mesenteri c lymph node cells and intestinal intraepithelial lymphocytes (IEL) in Strongyloides ratti-infected mice. On days 7 and 12 post-infection, 2 .6 times as many mesenteric lymph node cells were present in S. ratti- infected mice compared with uninfected mice. Although the percentages of CD3(+), CD4(+) and CD8(+) cells decreased during infection, the abs olute numbers of these cell types increased on day 7 due to an overall increase in the mesenteric lymph node cell number. The CD4/CD8 ratio in IEL was increased on day 5, whereas no significant change in the CD 4/CD8 ratio was observed in the mesenteric lymph node cells. Expressio n of IL-3 mRNA, which is an important cytokine for the induction of mu rine mucosal mastocytosis and S. ratti-expulsion, was examined in mese nteric lymph nodes and IEL of uninfected and infected mice. IL-3 mRNA was detected in mesenteric lymph nodes of S. ratti-infected mice but n ot detected in the lymph nodes of uninfected mice. IL-3 mRNA was detec ted in IEL from both infected and uninfected mice with an 20-fold incr ease in expression in IEL of infected mice. Overall, IL-3 mRNA levels were higher in IEL than in mesenteric lymph nodes following S. ratti-i nfection. Expression of IL-4, IL-10, stem cell factor (SCF or c-kit li gand) and IFN-gamma mRNA was also examined in these two tissues. IL-10 mRNA was not detected in any tissue examined and IFN-gamma mRNA level s were unaltered as a result of an S. ratti-infection. Elevated expres sion of mRNA for SCF (5-fold) and IL-4 (20-fold) was observed in the m esenteric lymph nodes of infected mice. in contrast, SCF mRNA levels w ere similar in IEL of uninfected and infected animals and only a modes t increase in IL-4 mRNA was observed in IEL of infected mice.