REACTIVATION OF MURINE TUMOR-INFILTRATING LYMPHOCYTES WITH SOLID-PHASE ANTI-CD3 ANTIBODY - IN-VITRO CYTOKINE PRODUCTION IS ASSOCIATED WITH IN-VIVO EFFICACY

Previously we described the use of solid-phase anti-CD3 monoclonal ant ibody (mAb) to stimulate murine tumour-infiltrating lymphocytes (TIL) and their subsequent expansion in recombinant interleukin 2 (rIL-2). I n a pulmonary metastases model using the methylcholanthrene-induced sa rcoma MCA-105 anti-CD3 activated TIL were capable of eradicating disea se similar to TIL cultured in rIL-2 only. Here we extend these observa tions by characterizing the biological effects of sequential solid-pha se anti-CD3 activation. TIL from MCA-105 tumour activated with solid-p hase anti-CD3 on day 1 were reactivated on day 14, or day 26, or both and compared to TIL grown in rIL-2 only or TIL activated with anti-CD3 once on day 1. Reactivation enhanced in vitro proliferation 1.8- to 4 -fold compared to TIL activated once with anti-CD3 (P < 0.05). In addi tion, the total lytic capacity of the cultures was enhanced after reac tivation without changing the phenotype of the TIL cultures. Reactivat ion resulted in a greater in vivo efficacy when the TIL were administe red within 72 h of reactivation. In contrast, TIL activated with anti- CD3 on day 1 and day 14 were least effective of all TIL cultures (P < 0.05). This correlated with in vitro cytokine production. The most eff ective TIL cultures in vivo produced 4- to 100-fold higher amounts of cytokines, especially interferon gamma (IFNgamma) and granulocyte macr ophage colony stimulating factor (GM-CSF), than the other cultures. On the other hand, the least effective in vivo TIL culture, TIL activate d with anti-CD3 on day 1 and 14, produced little or no cytokines. Thes e data suggest that in vitro production of cytokines is indicative of in vivo efficacy of anti-CD3 activated TIL.