[Determination of T-cell clonicity by a T-cell receptor gamma-chain: final data].

AIM: To test diagnostic efficacy of T-cell clonicity determination by a gamma-chain of T-cell receptor (TCR). MATERIAL AND METHODS: The examination covered 426 patients (458 tests). T-cell tumors were detected in 132 patients. The samples from 294 patients in whom T-cell tumors were not found were referred to the laboratory for a differential diagnosis. Clonicity was determined by gamma-chain of TCR in the test for conformation polymorphism of one-chain DNA fragments. All the tests were made in one laboratory. RESULTS: Sensitivity of the method, found by analysis of different delusions of the cell line Jurkat in selected polyclonal CD3+ cells is 10%. The results were of 3 kinds: clonal, doubtful and polyclonal. In patients free of T-cell tumors there were 15 (5%), 34 (11%) and 258 (84%) false positive, doubtful and true negative results. False positive results were most frequent in an acute phase of infectious mononucleosis--in 8 (33%) of 24 patients. 127 (84%) true positive, 5 (3%) doubtful and 19 (13% 0 false negative results were documented in patients with T-cell lymphoma. The occurrence of false negative results was the highest in anaplastic CD30+ T-cell lymphomas--in 6 (46%) of 13 cases. CONCLUSION: Diagnostic efficacy of the method is 92%, but in 10% the result is doubtful. Main reason of false negative results is a small number of tumor cells in tissue samples. The main reason of false positive results is prevalence of one or some T-cell clones in the presence of immune response caused by viruses, autoimmune diseases and, possibly, depletion of bone marrow in aplastic syndromes.