HAIRY-CELL LEUKEMIA WITH T-CELL FEATURES

Abstract

A case of clinically and hematologically typical hairy cell leukemia [HCL] was presented in which, at the various times of testing, 52%-95% of peripheral blood and 73% of splenic mononuclear cells formed spontaneous sheep erythrocyte (E) rosettes. Many of the rosetting cells were typical morphologic hairy cells by light microscopy and EM. Seventy to seventy-five percent of peripheral blood mononuclear cells stained with an anti-T [thymocyte] antiserum, and this antiserum also abolished E-rosette formation. A variable percentage of peripheral blood mononuclear cells also bore surface (IgDK) and internal (IgMK and IgGK) immunoglobulins. Additional B[bone marrow-derived]-cell features demonstrated included possession of the P29/34 Ia-like antigen and formation of mouse rosettes. A variety of blocking and inhibition studies showed that the E-rosette formation was not attributable to chance antigen specificity of the surface membrane Ig. These marker studies suggest that this is a case of true hybrid cell HCL. Despite these unusual marker characteristics, the patient showed no distinctive clinical or hematologic features.