Allogeneic bone marrow transplantation-mediated transfer of specific immunity against Toxocara canis associated with excessive IgE

A girl with myelodysplastic syndrome (RAEB-T) received HLA-identical bone m arrow from her younger brother after myeloablative treatment with busulfan and cyclophosphamide. After bone marrow transplantation, fever, exanthema, pruritis, and a pulmonary infiltrate were treated symptomatically. Bacteria l cultures remained negative. Leukocyte engraftment began on day 10, and al l blood cell populations proved to be of donor origin on FISH analysis. Inc reasing IgE levels (21 000 U/ml) on day 14 after BMT, positive RAST, specif ic IgG-antibodies, and missing Toxocara (T.) canis antigens in the recipien t indicated donor-derived seroconversion. Before BMT, the recipient had bee n negative for T. canis in routine parasitological screening, and the donor proved to be positive for T. canis antibody by ELISA. This report suggests that the transfer of IgE immunity in the absence of detectable antigens ma y be responsible for IgE-mediated symptoms consistent with toxocara infecti on and confirms the need for parasite screening in donor medical examinatio ns.