We have previously demonstrated that administration of recombinant rIL-1 alpha enhances resistance against Listeria monocytogenes infection in mice. In this study we considered the possibility that this cytokine might also augment adoptive immunity conferred by the transfer of listeria-immune spleen cells. Concomitant administration of rIL-1 alpha with large numbers (2 x 10(7) or 10(8)) of listeria-immune spleen cells reduced the protection mediated by the transferred cells. Conversely, rIL-1 alpha co-administered with suboptimal numbers (1-5 x 10(6)) of immune splenocytes augmented anti-listeria resistance in an additive fashion. Although transfer of 10(6) listeria-immune spleen cells alone did not result in significant protection, when 10(6) immune cells were incubated with rIL-1 alpha prior to transfer they conferred significant protection to naive recipients. Time course experiments indicated that the greatest protection was achieved when listeria-immune spleen cells were pretreated with rIL-1 alpha for 2 h prior to adoptive transfer. The protection transferred by 10(6) rIL-1 alpha-pretreated immune spleen cells was not inhibited by TGF beta. This study is the first to use rIL-1 alpha to potentiate the adoptive transfer of resistance to an infectious agent by immune cells.