Recurrent T cell receptor rearrangements in the cytotoxic T lymphocyte response in vivo against the P815 murine tumor

P815 is a murine mastocytoma of DBA/2 origin which, although immunogenic, rapidly develops as a tumor in immunocompetent syngeneic hosts. In this report, we have studied, by a molecular approach, the in vivo alpha/beta T cell response to P815. Both situations of tumor growth after engraftment of naive animals or tumor rejection by preimmunized animals have been analyzed. The spectrum of T cell receptor beta chain rearrangements in the tumor-infiltrating lymphocytes was found to be highly variable among individual tumor-bearing mice. However, two rearrangements, one using V beta 1 and J beta 1.2 segments and one using the V beta 1 and J beta 2.5 segments, with conserved junctional regions, reproducibly emerge in most individuals. These two rearrangements thus correspond to ''public'' (recurrent) T cell clones, as opposed to ''private'' ones, which emerge in a seemingly stochastic fashion in immunized animals. Importantly, these public cells are observed in situations of either growth or rejection of the tumor. Quantification provides a clear increase in public T cells in secondary responses, but no obvious correlation between their level and primary tumor rejection. The V beta 1-J beta 1.2 rearrangement is borne by CTL directed against an antigen derived from P1A, a nonmutated mouse self protein which is expressed in P815 but not in normal mouse tissues except testis. A recurrent, public T cell response can thus be observed to an antigen derived from a self protein expressed by a tumor.