Monoclonal antibody-defined T-cell subsets in hairy-cell leukaemia.

In 17 tests in 14 patients with hairy-cell leukaemia (HCL), peripheral blood Leu 2a+ and 3a+ suppressor and helper cells were present in normal mean percentage (3a+ 63 +/- 15%, normal 64 +/- 8%; 2a+ 39 +/- 16%, normal 34 +/- 8%), absolute (3a+ 0.8 +/- 0.4 x 10(9)/1, normal 0.6-1.4 x 10(9)/1; 2a+ 0.5 +/- 0.4 x 10(9)/1, normal 0.2-0.6 x 10(9)/1), and relative (3a+/2a+) (2.2 +/- 1.3, normal 1.9 +/- 0.7) numbers. In all the 9 untreated patients, 3a+ helper cells were normal or increased in percentage numbers, while 2a+ suppressor cells were normal or slightly reduced. It is suggested that these data explain, at least in part, the lack of immuneparesis of HCL as compared with chronic lymphocytic leukaemia (CLL) which is consistently associated with immuneparesis and an excess of Leu 2a+ suppressor cells. In individual splenectomised patients, some variations in Leu 2a+ and 3a+ numbers were observed, and it is suggested that the spleen, known to be important in the natural history of HCL, may have an influence on peripheral T-cell subsets. Although HCL is clearly shown to differ from CLL and myeloma regarding T-cell subset numbers, the fundamental mechanism underlying this difference remains unknown.