The effect of anti-interleukin 2 monoclonal antibody treatment on the survival of rat cardiac allograft

The effect of anti-interleukin 2 monoclonal antibody (anti-IL2 MoAb) and the accumulation of intravenously administered ¹²⁵I-labeled anti-IL2 MoAb were examined in heterotopic rat cardiac allografts. Mouse anti-human recombinant IL2 MoAb was obtained by the hybridoma technique. The anti-IL2 MoAb, termed 8H-10, was an IgG2a which inhibited IL2-driven [³H]TdR incorporation in cytolytic T lymphocyte line cells at a dilution of 2⁶. 8H-10 was injected iv at a dose of 200 μg/day for 8 consecutive days, beginning on the day of transplantation. Hearts from F344 rats (RT1^1v1) were transplanted into ACI recipient rats (RT1^1v1). The mean survival time was 7.6 ± 0.8 days in untreated controls, 9.0 ± 1.2 days in additional controls treated with mouse anti-sheep red blood cell monoclonal antibody, and 25.3 ± 18.4 days in the anti-IL2 MoAb (8H-10)-treated group (P <0.05). Furthermore, the accumulation of intravenously administered ¹²⁵I-labeled anti-IL2 MoAb (8H-10) was specifically seen in the grafted heart. In conclusion, these results suggest that IL2 may play an important role in allograft rejection and that anti-IL2 MoAb may serve as a useful immunosuppressive agent in clinical transplantation.