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Abstract This report provides the first evidence that lymphoblasts from different patients with acute lymphocytic leukemia (ALL), which are indistinguishable by cytomorphology, have membranes with different properties, such as the presence of thymus dependent (T) cell surface markers. In this study T cells were determined by spontaneous rosette formation with sheep erythrocytes and B (thymus-independent) cells by immunofluorescence of surface immunoglobulins. Of four children with untreated ALL, one had 62% lymphoblasts with T markers in bone marrow. Neoplastic cells with T markers were absent in the other three. None of these patients had lymphoblasts with B markers. In contrast, B and T lymphocytes were present in the blood and bone marrow of 24 children with ALL in remission and off therapy. None of these children had a mediastinal mass, but analysis of initial clinical manifestations suggested a more aggressive or extensive disease in the patient with T lymphoblasts. These data indicate that in some patients with ALL the neoplastic cells may be of thymic origin.
Borella et al. (Mon,) studied this question.