Donor-specific transfusion with diminished sensitization.

Fourteen mixed lymphocyte culture (MLC)-reactive haploidentical recipients have received donor specific transfusions (DSTs) with diminished sensitization to HLA antigens. A single unit of donor blood was obtained in CPD-A anticoagulant, packed, and transfused in three aliquots at 1-week intervals when the blood was 1, 3, and 5 weeks old. Transplantation, performed 22 to 149 days after the last DST, has been successful in all patients for 3 to 26 months except for one experiencing hyperacute rejection despite a negative crossmatch. In vitro studies suggest that blood storage results in the loss of T lymphocytes, which are presumably responsible for the sensitization, and preservation of B cells and monocytes, which remain capable of stimulating a cellular immune response in vitro throughout the 30-day storage period. Apparently this change in the cellular characteristics of blood with storage produces the salutory effects of blood transfusion without the undesirable sensitization to HLA antigens. The mechanisms remain under study.

Fresh versus stored blood in donor specific transfusion.

Haploidentical, MLC responsive recipients were randomized to receive either fresh (less than 48 hours old) or stored donor specific transfusions (DST). In the stored DST group, one donor unit obtained with CPD-Adenine anticoagulant was split into three aliquots and administered as packed cells after 1, 3, and 5 weeks of storage. While 3/6 fresh DST recipients became sensitized to their donors, 0/12 receiving stored DSTs developed positive donor crossmatches. Eleven patients (three fresh, eight stored) have been transplanted and have had similar posttransplant courses. None of the stored DST recipients has rejected his transplant. Four recipients of stored DSTs are awaiting transplantation. Leukocyte enumeration and FACS analysis of aliquots of stored blood shown that cells bearing HLA-ABC antigens disappear with time while B cells and monocytes persist. Taken in concert, the observations suggest that favorable recipient conditioning for transplantation can take place without sensitization to HLA antigens by simply storing the blood prior to transfusion.