[Application of Y-chromosome specific DNA analysis for detection of mixed hematopoietic chimerism after allogeneic bone marrow transplantation].

We report a case involving mixed hematopoietic chimerism after an allogeneic bone marrow transplantation (BMT) from a sex mismatched donor. A 31 year-old-man who was diagnosed as having chronic myelogenous leukemia in the accelerated phase received an allogenic BMT from his HLA-identical sister in March, 1989. To determine the mixed chimerism we used the Y-chromosome specific repeated sequence of DNA using a specific probe (PHY 10). The donor's DNA 3.5 kb band appeared in 1-10% of male DNA by Southern blot hybridization in the peripheral blood 21 days after BMT. The Y-chromosome DNA band decreased day by day, and disappeared 110 days after BMT. The Y-chromosome DNA band could be detected, even though few metaphases were obtained immediately after BMT. Thus this method is very sensitive for determining which cells contain the Y-chromosome, and is therefore useful for detecting mixed chimerism after sex-mismatched BMT. Using this method the clinical significance of mixed chimerism can be assessed.