TCR Vβ usage and clonality of T cells isolated from progressing and rejected tumor sites before and after in vitro culture

A gelatin sponge model of concomitant tumor immunity was employed in order to examine the clonality of T cells associated with progressing and rejected tumor sites. Here we show that freshly isolated T cells bearing TCR Vβ1, CDR3 RPGTGN, Jβ1.1 and TCR Vβ8, CDR3 GD, Jβ1.6 predominated progressing and rejected tumor sites. Despite the similarity in T cell populations, the T cells from rejected tumor sites were capable of killing the autologous tumor cells, whereas T cells from progressing tumor sites were not able to do so. The differing cytolytic ability could not be attributed to a difference in TCR ζ chain protein expression levels between both T cell populations. After a 5 day mixed lymphocyte tumor culture the T cells from the progressing tumor site were capable of killing autologous tumor cells, which suggested changes took place within the cell population during in vitro culture. Further TCR analysis revealed T cells bearing TCR Vβ1, CDR3 RPGTGN, Jβ1.1 and TCR Vβ8, CDR3 GD, Jβ1.6 were not expanded following the in vitro culture. These data suggest that the lack of cytotoxicity of freshly isolated tumor-infiltrating lymphocytes (TIL) was not due to abnormal TCR ζ chain expression or major differences in the TCR Vβ usage. Additionally, the gain of TIL effector function did not correlate with an expansion of the TCR bearing T cells found to predominate the in vivo response. These data suggest that the predominant TCR Vβ used by lymphocytes infiltrating regressing or rejected tumors may not represent the tumor reactive T cells that grow in culture or respond to the autologous tumor in vitro.