Infant leukemia: an analysis of nine Chinese patients.

A study was made of the cellular and molecular characteristics of nine Chinese infants, consecutively presenting with acute leukemia. Five cases were acute lymphoblastic leukemia (ALL); four were acute nonlymphoblastic leukemia (ANLL). Hyperleukocytosis, hepatosplenomegaly, and poor response to conventional therapy were common features, and CNS involvement was detected at diagnosis in three cases. The blast cells from all five cases with ALL expressed early B-cell markers, i.e., HLA-DR+, CD19+, but CD10-. Terminal deoxynucleotidyl transferase (TdT) was present in blasts from four of the five cases and periodic acid-Schiff staining in blasts from two patients only. The leukemic cells of one patient also showed positive nonspecific esterase activity and expressed myeloid-associated antigens CD33 (My9), CD11 (OkM1), and CD14 (My4 and Mo2). Molecular analysis of leukemic cell DNA from this and two other patients showed rearrangement of the immunoglobulin (Ig) heavy-chain genes, but without any evidence of kappa light-chain gene rearrangement. T-cell receptor (TCR) genes remained in the germline configuration in these cases. Cytogenetic analysis showed translocation t(4;11) (q21;q23) in all four cases studied. In the group of ANLL, three cases belonged to the M4 and one to the M2 subtype. Chromosomal abnormality involving 11q23 was also detected in two patients: t(11;17)(q23;q11) and del(11)(q14q23) in each case respectively. Neither Ig nor TCR gene rearrangement was present in blast cells from patients with ANLL. The data indicate that chromosomal rearrangement of band 11q23 was quite common in Chinese infants with either form of leukemia, a finding that may have pathogenetic implications.