Anti-idiotypic antibodies against UV-induced tumor-specific CTL clones. Preparation in syngeneic combination

In this study, we first established several CTL clones of (BALB/c x C57BL/6)F₁ origin that were specific for either syngeneic UV♀1 or UV♂1 fibrosarcoma cell lines. All the CTL clones had Thy-1⁺ Lyt-2⁺ L3T4^- phenotypes and showed K(d) restriction when lysing the corresponding target cells. Sera obtained from syngeneic animals immunized with three CTL clones, 10B-5 for UV♀1, and CTL9 and CTL10 for UV♂1, showed specific inhibition of target cell lysis with the corresponding CTL clones. The inhibitory activities were found in sera of the majority of immunized animals. Because the inhibitory activity resides in protein A-binding fraction, mAb were produced by hybridizing spleen cells of hyperimmune animals. N1-56 was thus obtained from a mouse immunized with 10B-5 CTL clone reactive with UV♀1. N1-56 was clonotype specific, reacting with 10B-5 but not with other CTL lines or leukemia cell lines. No N1-56⁺ cells were detectable in thymocytes, lymph node cells, or spleen cells of either naive or UV♀1-immune CB6F₁ mice. Immunoprecipitation showed that N1-56 reacts with 90,000 M(r) molecules on 10B-5 CTL clone under nonreducing conditions and 45,000 M(r) molecules under reducing conditions, indicating its reactivities with idiotypic determinants of TCR on the CTL clone. N1-56 inhibited lytic activity of 10B-5, but neither N1-56 nor α-10B-5 hyperimmune serum inhibited that of α-UV♀1 mixed lymphocyte tumor cell culture cells. N1-56 induced proliferation of 10B-5 without addition of Ag.