OLIGOCLONALITY OF CD8(-CELLS IN BREAST-CANCER PATIENTS() T)

Substantial evidence has suggested that T cells play an important role in antitumor immunity. T cells with cy totoxic activity against tumor s have been isolated from in vitro culture of tumor-infiltrated lympho cytes of cancer patients. In addition, clonal expansions of T cells ha ve been identified in lesions of tumors by using a PCR-based CDR3 anal ysis of T cell receptors (TCR). Since the CDR3 region of the T cell re ceptor directly interacts with the antigen-MHC complex and is thus hig hly polymorphic, a dominant CDR3 length in a particular TCR V beta pop ulation will indicate the clonal expansion of a specific T cell clone. Utilizing this technique, we have analyzed the T cell repertoire in l ymph nodes (LNs) and peripheral blood of 20 breast cancer patients. Ou r results show that in most cases, peripheral blood mononuclear cells (PBMCs) and LN express dominant CD8(+) T cell clones in different V be ta gene families, and the number of dominant clones is higher in PBMC than in the LN. Furthermore, in 7 out of 16 patients' lymph nodes, the re is a dominant V beta 18 T cell clonal expansion in the CD8(+) T cel l subset. The frequency of an oligoclonal expansion of V beta 18 CD8() T cells in non-breast cancer lymph nodes is 1 out of 9, but no obvio us motif in the CDR3 region of V beta 18 TCR can be identified. The pr evalence of the clonal dominance found in breast cancer is discussed i n the context of a possible tumor-related antigen stimulation.