Participation of a dominant cytotoxic T cell population defined by a monoclonal antibody in syngeneic anti-tumor responses*
Cytotoxic T lymphocyte (CTL) clones against a syngeneic Friend virus-induced erythroleukemia (FBL-3) were generated in C57BL/6 (B6) mice. A monoclonal antibody (mAb, N9-127) was then raised from spleen cells of a B6 mouse immunized syngenically against one of these CTL clones.This mAb detected the epitope (127Ep) of the T cell antigen receptor (TcR) on the immunizing CTL clone in tests of immunoprecipitation, specific blocking and proliferation, and induction of TcR-mediated nonspecific lysis of the clone. In addition, more than 10% of the FBL-3-specific CTL clones isolated independently from B6 mice were 127Ep+. Further investigations revealed that up to 30% of B6 anti-FBL-3 Tcell blasts from mixed lymphocyte tumor cell cultures were positive for this epitope, and that its expression was confined to CD8+ T cells. This epitope was not detected in naive lymphoid cells from the spleen, lymph nodes or thymus or in T cell clones specific for tumors other than FBL-3. The FBL-3-specific CTL clones were next grouped into 127Ep+ and 127Ep-clones. Sequence analyses of the CTL clone used for immunization showed the rearrangements of Va1Ja112-2 and VglODg2.1Jg2.7. Southern blot analysis of all the 127Epf CTL clones examined showed the same DNA rearrangement bands of both the TcR a and p genes. These findings suggested that mAb N9-127 recognized the shared determinant of the TcR molecule which was expressed by the dominant CTL population in the response to FBL-3. * This work was supported by Grants-in-Aid for Cancer Research from the Ministry of Education, Science and Culture Of Japan.
Recently, we showed that anti-idiotypic antibodies were generated against the TcR of UV-induced tumor-specific CTL clones, but these antibodies detected only a very low frequency of cells bearing the idiotype [12]. In the present determinant defined by a mAb designated as N9-127 which recognized a TcR expressed in appreciably high frequency by CD8+ T cells responding to the C57BLI6 (β¬36) FBL-3