Short lived, dividing cells mediate adoptive transfer of immunity to Trichinella spiralis in mice. II. In vivo characteristics of the cells.

The in vivo characteristics of mesenteric lymph node cells (MLNC) capable of mediating the adoptive transfer of immunity to Trichinella spiralis have been examined. Mediator cells were diverted into the peritoneal cavity of infected donor mice following the induction of a peritoneal exudate and its was shown that these were nylon-wool, non-adherent (T) cells. After density gradient separation of [125I]-UdR-labelled MLNC, the fractions that were most effective in transferring immunity were those containing a small proportion of cells but the largest proportion of incorporated activity. Treatment of the donors of MLNC with the mitotic inhibitor vinblastine effectively prevented both the transfer of immunity and increased incorporation of [125I]-UdR characteristic of the mediator population. In vitro irradiation of MLNC failed to affect their ability to transfer immunity. Collectively these findings support the conclusion that mediator cells are T lymphoblasts, and suggest that mediation of immunity is effected directly by this population and not by their progeny.