A case of infantile acute monocytic leukemia caused by vertical transmission of the mother's leukemic cells

A case of infantile acute monocytic leukemia (AMoL), which was probably transmitted from a pregnant woman with leukemia to her unborn infant, is presented. A woman had AMoL when her third infant was born. This infant, who was a boy, also suffered from AMoL when he was 20 months of age. The infant's leukemic cells had the same cytochemical and immunophenotypic patterns as the mother's leukemic cells. By cytogenetic analysis, the majority of the infant's leukemic marrow cells had the 46,XX karyotype and showed no Y body by quinacrine staining. Moreover, the phenotype for human major histocompatibility system, HLA-A, HLA-B, and HLA-DR of the infant's leukemic cells was consistent with that of the mother's lymphocytes. Thus, the infant's leukemic clone was found to be identical to the mother's leukemic clone. His lymphocytes could not react with the mother's leukemic cells or his own leukemic cells in mixed lymphocyte culture, suggesting that the HLA homozygosity of the mother may have played a role in inducing immunologic tolerance to the immigrated leukemic cells in the infant. This is the first report of an infantile leukemia transmitted from a mother with leukemia, supposedly through the placenta.