DEFECTIVE TCR SURFACE EXPRESSION ASSOCIATION WITH IMPAIRED TCR BETA-CHAIN ASSEMBLY IN A PATIENT WITH CUTANEOUS T-CELL LYMPHOMA

We report on a patient with cutaneous T-cell lymphoma (CTCL) of long-s tanding duration. Phenotypic analysis of his peripheral blood mononucl ear cells revealed an increased CD4(+) T-helper subset and a decreased CD8(+) cytotoxic T-cell population. Eighty-three to ninety-three perc ent of the patient's CD4(+) T cells in the peripheral blood and 70% of the CD4(+) T cells in the lesional skin lacked surface expression of the TCR/CD3 complex and showed a clonal rearrangement pattern of the T CR gamma-chain gene (V11-J1/J2). The lack in TCR surface expression co rrelated with defective assembly of the TCR beta-chain. Although mRNA for the TCR constant region beta 1 was found in the patient's purified CD4(+)TCR(-)CD3(-) T cells, no intracytoplasmic TCR beta protein was detectable. In contrast, the patient's purified CD4(+)TCR(-)CD3(-) T c ells not only expressed mRNA specific for the TCR alpha-chain and for all CD3 chains, but intracytoplasmic TCR alpha and CD3 epsilon protein s could also be found. The lack of TCR beta protein clearly explains t he defective surface expression of the TCR/CD3 complex in the patient' s malignant T cells.