The role of OX22- helper T cells in protective immunity to reinfection with Taenia taeniaeformis in rats.

Spleen cells (SpC) and mesenteric lymph node cells (MLNC) from F344 donor rats actively immunized by oral inoculation with Taenia taeniaeformis eggs were syngeneically transferred into previously uninfected recipient rats by intravenous injection. Recipient rats were challenged with eggs after cell transfer. The degree of immunity was assessed by counting the number of growing metacestodes (MC) in the liver and compared with that in controls. Transfer of 2 x 10(8) SpC, obtained from donors immunized for ten or more (but not for three or five) days before cell transfer inhibited the establishment of most of MC. There were approximately 86-88% reductions in MC recoveries. SpC (2 x 10(8)) obtained from donors immunized for ten days inhibited the establishment of most of MC in recipient rats when transferred nought, two, or 24 h (but not 48 h) before egg challenge. Functional cells in the immune SpC were helper T cells W3/25+, OX8- and OX22-. However, immune MLNC obtained from donors immunized for three to ten days before cell transfer had no effect on transferring immunity.