Autologous lymphoid cells exposed to recombinant interleukin-2 in vitro in the absence of antigen can induce the rejection of long-term tolerated skin allografts.

The intraperitoneal (i.p.) administration of autologous spleen cells treated with recombinant interleukin-2 (IL-2) in vitro resulted in the rejection of C57BL/10ScSn (B10) skin grafts that had survived for 18 months on CBA/Ca mice tolerant to B10 alloantigens. Cytotoxic lymphocytes specific for the graft alloantigens, assayed by limiting dilution analysis, appeared after the breaking of this immunological tolerance, whereas they were not detectable in tolerant mice. In these mice the frequencies of precursor cytotoxic cells specific for third-party alloantigens were unaffected by the IL-2 treatment.