Subpopulations of human T lymphocytes VI. Analysis of cell markers in acute lymphoblastic leukemia with special reference to Fc receptor expression on E-rosette-forming blasts

Abstract
A variety of surface markers, terminal deoxynucleotidyl transferase (TdT) activity, morphologic appearance, and cytochemical composition were studied in a group of 16 patients (13 children, 3 adults) with acute lymphoblastic leukemia (ALL). In 9 children, no surface markers were detected on lymphoblasts (null‐type ALL). Leukemic blasts of 4 children formed E‐rosettes. These E‐rosette‐forming blasts from childhood ALL, and E‐rosette‐forming lymphoblasts from 3 adult patients with ALL, were studied for the presence of Fc receptors. Of the leukemic blasts from these 7 patients, 2–76% expressed receptors for IgG Fc. Only 3 of 7 patients showed 9–42% receptors for IgM Fc. In addition, complement receptors were investigated in 6 of those 7 patients with T‐cell ALL. Complement receptors were detected on 9–70% of the E rosette forming blasts from all 6 patients. TdT activity was elevated in T‐cell ALL and in children with null‐type ALL. The heterogeneity of Fc receptor expression on leukemic blasts in these patients demonstrates a malignant proliferation of T cells in different stages of differentiation or maturation. This observation might be helpful in subclassifying T‐cell leukemias with regard to prognosis and the response to therapy. Cancer 46:45–49, 1980.