The structure of the T cell antigen receptor genes in normal and malignant T cells.

In this review the genomic structure and the RNA transcripts of the alpha and beta chain of the T cell antigen receptor have been discussed. Studies of the structure of TcR beta in hematologic malignancies have revealed rearrangement in almost all of the T cell malignancies and a small proportion of non-T cell malignancies. In addition, clonal involvement of T cells in diseases such as Hodgkin's disease, angioimmunoblastic lymphadenopathy, and chronic T cell lymphocytosis have been observed. The study of the structure of the TcR beta gene is thus a useful tool for identifying clonal expansions of cells and in conjunction with studies of the immunoglobulin gene structure, and cell surface markers a useful tool for identifying cell lineage. At the present time the evaluation of the structure of the alpha chain genes has not been as fruitful. However, chromosome translocations involving the TcR alpha chain genes have been recognized and, in one case, this rearrangement has been in association with a known oncogene. With the isolation of more probes to the alpha chain region it should be possible to test its utility in identifying clonal populations and cell lineage. The recent isolation of the gamma gene of the T cell will also permit such studies. Preliminary results of studies carried out with a probe to the gamma chain gene of the T cell have paralleled results obtained with the TcR beta probe (unpublished observation).