Abstract
Since the prognosis of infants with acute lymphoblastic leukemia (ALL) is so poor, it has been suggested that these leukemias may not be lymphoid in origin, but may originate from stem cell, myeloid, or megakaryocytic progenitors. Alternately it has been hypothesized that these leukemias originate in lymphoid cells at the earliest stages of B cell development. Another possibility is that these leukemias may be of more than one lineage. Therefore we examined leukemic blasts from 12 infants with ALL using monoclonal antibodies to myeloid and lymphoid differentiation antigens. The majority of specimens expressed HLA/DR and reacted with B4 (CD19) but failed to react with stem cell, myeloid, megakaryocytic, or T cell associated antibodies. These results support the speculation that the majority of these leukemias arise in cells at the earliest stages of B cell commitment, and are not of a myeloid or biphenotypic nature.
