T cell gamma chain gene rearrangement without T cell receptor beta chain gene rearrangement in two cases of non-Hodgkin's lymphoma.

We report two patients with non-Hodgkin's lymphoma whose neoplastic cells had rearranged T cell gamma chain (T gamma) genes, and had the germ line DNA of T cell receptor beta chain (T beta) and immunoglobulin genes. Surface marker analysis of the neoplastic cells revealed that leukemic cells from one patient were derived from common thymocytes, while in the other patient the clonality and cell lineage could not be identified, probably due to the low percentage of neoplastic cells in the specimen. No phenotypic changes were observed after cultivation with phorbol myristate acetate, except for induction of Tac antigens on cells of one patient. Leukemic cells with only the T gamma gene rearrangement are thought to be precursor T cells that differentiate into mature T cells following T beta gene rearrangement. This suggests that such T cells with only the T gamma gene rearrangement exist among common thymocytes.