[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.