Passenger lymphocyte syndrome with hemophagocytic syndrome after peripheral blood stem-cell transplantation from an HLA-matched full biological sibling: case report.

Massive hemolysis due to passenger lymphocyte syndrome (PLS) is rare after peripheral blood stem-cell (PBSC) transplantation with a minor ABO mismatch. We present, in a 16-year-old boy (group A Rh+), PLS with hemophagocytic syndrome (HPS) after PBSC transplantation from his HLA (human leukocyte antigens)-matched biological sister (group O Rh+). Mild-to-moderate hemolysis was evident from day +11 to day +15 after transplantation. HPS was diagnosed by bone marrow examination on day +16, while antibodies against the recipient's red blood cell antigens were detected on days +15 and +27. This hemolysis may have been due to PLS with HPS. Therefore, measurement of antibodies may provide a useful hallmark of immune hemolysis.