Configuration of the immunoglobulin and T cell receptor gene regions in hairy cell leukemia and B-chronic lymphocytic leukemia.

The configuration of the immunoglobulin heavy and light chain genes and of the T cell receptor (TCR) beta region was examined in a series of patients with hairy cell leukemia (HCL) and compared with the findings in B cell chronic lymphocytic leukemia (B-CLL). In all cases of HCL and B-CLL studied a rearrangement of the immunoglobulin heavy chain loci coupled to a reorganization of the light chain genes was documented. However, in all HCL and all but one B-CLL the TCR beta gene region was in a germ-line configuration. These findings confirm that HCL is characterized by the expansion of relatively mature B cell elements with a molecular configuration similar to that of B-CLL and indicate that the reported expression of T cell related markers, particularly in B-CLL, is not coupled to a rearrangement of the TCR beta-chain gene. Analyses of the immunoglobulin gene regions in HCL represent an important diagnostic tool as well as a possible aid toward monitoring the response to treatment.