ABO-incompatible bone marrow transplantation: preparation by plasma exchange and in vivo antibody absorption.

The threat of fatal hemolytic transfusion reaction has been a major deterrent to the use of ABO-incompatible bone marrow donors. An eighteen year old type O male with acute leukemia was prepared to receive type A HLA identical marrow using large volume plasma exchange prior to and following cyclophosphamide administration. Saline agglutinating anti-A antibody was initially present at a titer of 1:128. The initial antiglobulin titer of dithiothreitol (DTT) treated serum was 1:64. Initially the T 1/2 of 51Cr labeled type A red blood cells was less than five minutes. The first plasma exchange removed large quantities of anti-A antibody but 51Cr survival of type A red blood cells was unchanged. A second plasma exchange after an interval of three days, increased the T 1/2 of 51Cr labeled cells to 20 minutes. Saline agglutinating anti-A was not present at a titer of 1:8 and the antiglobulin titer of DTT treated serum was 1:4. Reaction to subsequent transfusion of type A red blood cells (5 units) was limited to a single febrile episode during the first unit. Survival of 51Cr labeled red blood cells increased to T 1/2 equal to 21 hours. These data indicate that plasma exchange and infusion of ABO incompatible red blood cells effectively reduce antibody concentration and prolong survival of ABO incompatible erythrocytes. It is suggested that the prolongation of 51Cr survival of ABO-incompatible red blood cells to a point that extravascular destruction is predominant be used to establish the safety of ABO-incompatible marrow infusion.