Characterization of T-lymphocyte subsets in hairy-cell leukaemia (HCL) by monoclonal antibodies: comparison with Fc gamma, Fc mu receptors and correlation with disease activity.

T lymphocytes from 22 patients with hairy-cell leukaemia (HCL) were assessed on the basis of their ability to bind the Fc receptors for IgM (T mu) or IgG (T gamma), and by the capacity to react with OKT monoclonal antibodies. T-cell subsets defined by the presence of Fc receptors for IgM or IgG showed an overall increase in the proportion of T gamma cells and a non-significant decrease of T mu cells, regardless of the clinical state of the disease. Results with monoclonal antibodies showed that in patients with HCL in clinical remission T-cell subsets were normally balanced, while in patients with active disease the distribution and absolute number of T-cell subpopulations appeared markedly impaired, with a significant increase of OKT8 positive cells (suppressor/cytotoxic) and a significant reduction of OKT4 positive cells (helper/inducer) compared both with active disease patients and with normal controls. The OKT4+/OKT8+ ratio was also significantly reduced in patients with active disease compared with those in clinical remission and with controls (0.96 v 1.63 and v 1.94, respectively). Our findings confirm the heterogeneity of T-cell subset positivity defined by monoclonal antibodies and by Fc mu and Fc gamma receptors and suggest that in patients with HCL the distribution of OKT4 and OKT8 positive cells is closely correlated to the clinical state of the disease.