Acute leukemias with both myeloid and lymphoid surface markers. Cytoplasmic alpha-1-anti-chymotrypsin and alpha-1-anti-trypsin as possible indicators of early granulocytic differentiation.

Blast cells from ten patients (seven adults, three children) with acute lymphoblastic leukemias (ALL) contained immunoreactive cytoplasmic alpha-1-anti-trypsin (alpha-1-AT) and alpha-1-antichymotrypsin (alpha-1-ACT). Cytochemically positive reactions for block-like periodic acid-Schiff and a localized acid phosphatase suggested that the cells were of lymphoid origin rather than myeloid origin: negative for sudan black-B, nonspecific esterase, chloroacetate esterase, and myeloperoxidase. By surface phenotype, the leukemia showed positive reactions for both lymphoid (common acute lymphoblastic leukemia antigen, Ia, OKT-10) and myeloid (OKM-1, Leu M-1) antigens. Three of three patients tested portrayed the Philadelphia chromosome. Nine patients were Mexican-American and one was Japanese: all were of Asian ethnic derivation. Both myeloid and lymphoid treatment regimens were employed, with survival less than expected. Early granulocytic differentiation detectable by cytoplasmic alpha-1-AT and alpha-1-ACT in lymphoid blasts is discussed.