T-cell lines specific for infective muscle larvae antigens of the intestinal nematode Trichinella spiralis have been generated in vitro. These antigen-specific T-cell lines express the L3T4+ Ly2- phenotype and secrete the lymphokines IL-2, IL-3 and gamma-IFN. They are stable in culture for up to 15 weeks and are protective when adoptively transferred into naive recipients. As few as 2 x 10(5) T. spiralis-specific tract. In addition, intestinal mastocytosis and peripheral blood eosinophilia were accelerated after adoptive transfer of T. spiralis-specific T-cell lines.