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The development of B cell lymphoma has been reported to occur in recipients of a variety of organ transplants, including some patients who have received an allogeneic bone marrow graft. In this report, we describe a patient with severe aplastic anemia who developed a malignant B cell lymphoplasmacytoid proliferation 48 days after undergoing allogeneic marrow transplantation from her HLA-matched MLC-nonreactive brother. Immunologic studies showed this malignancy to be a mixed polyclonal and monoclonal proliferation in donor cells. Virologic studies documented Epstein Barr infection of the cells. A review of the literature suggests that graft-versus-host disease and treatment of this complication by antithymocyte globulin are related to the development of the EBV-related malignancy in the EBV-infected B cells of the developing bone marrow graft.

We have studied the feasibility of using DNA restriction fragment-length polymorphisms (RFLP) to study marrow engraftment in 27 patients after allogeneic bone marrow transplantation, and have compared these results with those obtained using red blood cell antigens, cytogenetics, and immunoglobulin allotypes. Using highly polymorphic DNA probes, we have documented stable chronic mixed hematopoietic chimerism, have identified transient mixed chimeras, have excluded mixed chimerism with high probability in retrospective studies even when a pretransplant DNA sample was not available, have documented marrow engraftment in the early posttransplant period, and have studied the origin of leukemic cells in patients with recurrent disease. We have evaluated the advantages and disadvantages of several genetic markers and have developed tentative statements concerning the prognosis of patients with mixed chimerism. We conclude that DNA RFLP are powerful and practical genetic markers in bone marrow transplantation studies and that further studies of mixed hematopoietic chimerism are warranted.

The unlabeled antibody enzyme method, using the peroxidase-antiperoxidase immunocomplex for labeling, was applied to freshly prepared viable lymphocytes to detect antibodies in individuals preimmunized by pregnancies or blood transfusions. The "sandwich" incubations and washing steps were carried out with cells attached to poly(L-lysine) glass slides, in order to facilitate the handling of the samples and to save antisera and time. In comparison to the lymphocytotoxicity test, the described method is more sensitive and able to detect additional antibodies. Our findings indicate that further investigation of the use of this test for the demonstration of cell surface antigens and their antibodies appears to be worthwhile.

Twelve of 58 (21%) evaluable patients of blood group 0 who received a bone marrow transplant (BMT) from an HLA-matched sibling of a donor of group A or B developed significant immunohematologic problems in the posttransplant period. Anti-A or anti-B isohemagglutinins persisted for longer than 120 days post-BMT in nine patients and are still present in three patients at days +162 to +605. Red cell production as indicated by a reticulocyte count of greater than 0.5% was delayed to 40 days or more in nine patients, and in five of these was markedly delayed to 170 days or longer. One patient does not as yet have red cell production on day +605 in spite of having had 13 plasma exchanges performed to reduce the anti-B titer. Five patients experienced overt hemolysis, manifested by a sudden drop in hemoglobin of 1.5 to 4 gm/dl (median = 2.5 mg/dl), starting on day +37 to +105 (median = +65), persisting for 10 to 94 days (median = 36 days). Hemolysis and a delay in the onset of erythropoiesis beyond 170 days were more frequent in 30 patients treated with cyclosporine/prednisone than in 28 patients treated with methotrexate/prednisone for graft-versus-host disease prophylaxis. Our data indicate that ABO major mismatched BMT can be associated with significant immunohematologic consequences, some of which occur more frequently in association with cyclosporine administration.