Alloimmunization in preterm infants after repeated transfusions of WBC-reduced RBCs from the same donor

Preterm infants are among the most heavily transfused of patient groups, yet multiply transfused infants only rarely produce alloantibodies against RBC or WBC antigens. It is not known whether rates of alloimmunization might be increased by repeated exposure to RBCs and WBCs from the same donor, as in limited-donor-exposure programs, or whether infants might benefit from WBC-reduced RBC components as a means of diminishing the risk of possible alloimmunization.

Preterm infants (birth weight 0.6-1.3 kg) received prestorage WBC-reduced RBCs from dedicated donors, collected in AS-3 as a means of limiting donor exposures. Blood samples were collected serially from infants shortly after birth until either discharge or age 6 months and were studied for RBC and WBC antibodies-the latter with reactivity against either HLA class I or neutrophil-specific antigens.

Thirty preterm infants received 139 transfusions (mean, 4.6; median, 4 transfusions per infant), with 81 percent of transfusions obtained from one donor per infant. Eighty-four blood samples (mean, 2.7/infant) were studied, and no infant produced RBC antibodies. Twenty-seven percent of infants exhibited WBC antibodies, but only 13 percent actually produced WBC antibodies (passive maternal antibody excluded). Of the WBC antibodies produced by infants, three were against HLA class I and one was against neutrophil-specific antigens; none were linked to adverse effects.

Because infants only rarely produce RBC antibodies, no changes in blood banking practices are necessary for limited-donor-exposure programs. Although the production of WBC antibodies by infants occurs, it seems to be uncommon; thus, the possible benefits, if any, of WBC reduction are uncertain, and further study is required before changes in practice can be justified.