Intraintestinal migration to the epithelium of protective, dividing, anti-Trichinella spiralis CD4+ OX22- cells requires MHC class II compatibility.

We have measured the intraintestinal migration of activated Th cells belonging to the OX8- OX22- and OX8- OX22+ subsets derived from thoracic duct lymph of rats infected with Trichinella spiralis. Cells in S-phase were labeled with 125I-UdR or 3H-TdR in vitro and transfused i.v. Identical proportions of both helper cell subsets localized in the small intestine but three to four times as many OX22- cells as OX22+ cells migrated to the intestinal epithelium. Experiments using MHC class I and II recombinant rats indicated that localization of OX8- OX22- cells in the lower lamina propria (LP) and muscularis was reduced by 50% in MHC class II incompatible rats as assessed by total gamma-counts but by a factor of three when labeled cells were counted. Movement of labeled OX8- OX22- cells to the epithelium was reduced by a factor of five to seven when assessed by the same methods. Quantitative cellular localization in the gut and further movement to the epithelium were normal in class I-mismatched rats. The movement from the lower-mid LP to the epithelium was undertaken principally by dividing cells as indicated by a progressive loss of grain counts in labeled cells and the appearance of doublet-cells in mitosis. In allogeneic combinations, extravasating cells remained localized close to their primary site of exit in the muscularis and lower-mid LP. The results suggest that the requirement for MHC class II compatibility for adoptive transfer of immunity in rats to T. spiralis is functionally related to localization of the protective OX22- cell subset in the epithelium.