Role of T cell subsets in the maternal-to-neonatal transmission of immunity against Trichinella spiralis during lactation in rats.

We have previously demonstrated the maternal-to-neonatal transfer of immunity to T. spiralis during lactation and have shown that antigen-specific T lymphocytes, when injected into the mother or orally fed to neonates, can mediate this transfer. To further analyze the T cell subsets involved in conferring this protection, T lymphocytes were isolated from the mesenteric lymph nodes of syngeneic donor rats infected 4-6 days earlier with T. spiralis. The T cells were incubated in vitro with either mouse-anti-rat 0X8 or W3/25 monoclonal antibody, "panned" on plates coated with goat-anti-mouse Ig, and the non-adherent T helper or T cytotoxic/suppressor cells harvested. 100 x 10(6) T helper cells were injected i.v. into mothers once in early lactation and again two days prior to challenging their pups (200 T. spiralis larvae) at 2 weeks of age. This resulted in significant passage of immunity from the mothers to their suckling neonates, worm counts being 59% and 73% of control values 3 and 8 days post-challenge (P less than 0.01). Injection of T-cytotoxic/suppressor cells using the same regimen resulted in significant suppression of immunity in challenged pups, who retained worm counts that were 105% and 145% of control values at 3 and 8 days post-challenge. Synergy between recombined panned T-helper and T cytotoxic/suppressor cells without Ly1+2+3+ amplifier cells was tested by recombining non-adherent panned 0X8 and W3/25 cells. This resulted in no significant expressions of immunity in the pups when compared to controls. The presence of transferred maternal T cells within the neonate was evidenced by the fact that neonates (nursing on immune mothers) had significant (P less than 0.01) delayed footpad reactions to a crude T. spiralis antigen preparation, as compared with neonates nursing on non-immune controls.