Cellular mechanisms of immunity to the nematode Trichuris muris

Maximum increases in cell numbers in the mesenteric lymph node (MLN) of CBA/Ca mice were evident by day 20 post-infection with the parasitic nematode Trichuris muris, a time which correlates with the onset of worm expulsion. Mesenteric lymph node cells (MLNC) taken at this time (day 20) were most consistently effective at transferring immunity to naive animals (cells taken earlier or later were much less effective) and showed high levels of incorporation of radiolabelled thymidine (³H-thymidine) indicating blastic activity. At least 4 × 10⁷ unseparated MLNC were needed to transfer immunity, whereas 2 × 10⁷ but not 1 × 10⁷ T enriched cells transferred considerable protection. Nylon wool adherent (B enriched) populations had no effect. The immunity transferred by the MLNC was persistent even in the absence of antigenic stimulation, as evidenced by the accelerated expulsion of a delayed challenge (42 days after cell transfer). The results are discussed in terms of T cell mediated inflammatory responses in the small and large intestine.