L3T4-positive T lymphoblasts are responsible for transfer of immunity to Trichinella spiralis in mice.

The characteristics of lymphocyte subpopulations involved in mediating immunity to the intestinal nematode Trichinella spiralis in vivo have been examined using adoptive transfer in conjunction with accurate cell-sorting and cell-depletion techniques. Positive selection of cell subsets, using FACS sorting and velocity sedimentation at unit gravity, confirm that rapidly dividing T blasts are the major population that mediates expulsion of the worm from the gut. Furthermore, cell-depletion studies demonstrated that the T-cell subset involved is of the L3T4 + ve Lyt 2-ve phenotype. This phenotype suggests class II MHC restriction in recognition of T. spiralis antigens by T cells in vivo. The roles that such T cells play in immunity to T. spiralis are discussed in terms of lymphokine release.