Unusual T-cell phenotype in advanced B-chronic lymphocytic leukaemia.

T-lymphocytes isolated by E-rosetting from 22 patients with B-cell chronic lymphocytic leukaemia (B-CLL) showed membrane phenotype features distinct from those of normal T-lymphocytes. These changes were particularly marked in advanced disease (Rai stages II, III, IV and WBC over 100x10(9)/l). The most significant finding was the demonstration, in 10 cases, of a major population of E-rosette positive cells (40-80%) unreactive with the OKT monoclonal antibodies against mature or immature T-cells; 15-30% of the cells were unreactive in seven other cases. A significant reduction in OKT4 positive (helper) lymphocytes was seen in 18 cases. The proportion of OKT8 positive cells was increased in two and normal or low in the rest. Only four patients with early disease (stages 0 and I) had a normal T-cell phenotype. These findings could explain abnormalities previously described in the T-lymphocytes of B-CLL and provide new insights into the pathogenesis of the disease.