PREVENTION OF EBV-INDUCED B-LYMPHOPROLIFERATIVE DISORDER BY EX-VIVO MARROW B-CELL DEPLETION IN HLA-PHENOIDENTICAL OR NONIDENTICAL T-DEPLETED BONE-MARROW TRANSPLANTATION

HLA-mismatched bone marrow transplantation (BMT) is hampered by three major complications: graft rejection, acute graft-Versus-host disease (aGVHD) and delayed immune reconstitution, Infusion of anti-LFA1 plus anti-CD2 monoclonal antibodies (MAb), combined with ex-vivo T-cell dep letion of the graft, was efficient in preventing graft rejection and a GVHD, Nevertheless, disease-free survival was limited by the high freq uency of lethal infections, including EBV-induced lypmphoproliferative disease (BLPD), which originates mostly from donor B cells, with an i ncidence of 5-30%. To decrease the rate of this complication ex-vivo B -cell depletion was attempted. This study compares a group of 19 patie nts who received a T- and B-cell-depleted marrow from an HLA-mismatche d related donor with a retrospective control group of 19 patients, who had received T-cell-depleted marrow by the same method. The level of T-cell depletion was similar in the two groups. For B-cell depletion, two different methods were compared. The median number of B cells infu sed in the study group was 0.46/kg. Engraftment and aGVHD incidence we re similar in the two groups. No EBV donor-derived BPLD occurred in th e study group, compared with seven in the control group, four of whom died because of EBV-BPLD. Event-free survival was significantly differ ent between the two groups. We conclude that ex-vivo B-cell depletion of the graft may be a useful means of preventing EBV-BPLD, and warrant s further study on a larger group of patients.