Immune response to blood transfusion in very-low-birthweight infants

BACKGROUND: Allogeneic blood transfusion is common in the treatment of neonatal anemia of prematurity or anemia due to multiple phlebotomies. The immune response of neonates to passenger leukocytes from allogeneic red cells was investigated. STUDY DESIGN AND METHODS: Fourteen infants (4 male, 10 female) prospectively were randomly assigned to receive either white cell-reduced (Group 1) or nonwhite-cell reduced (Group 2) irradiated blood. Blood samples were taken before and at various time intervals after transfusion (Days 1, 5-7,and 10-14). Cord blood from 11 healthy term infants was used for comparison. The following surface markers were used to assess immune modulation by flow cytometry: CD45RA/CD45RO, CD4/CD8, CD25/CD28, CD3/DR, CD14/B7, and CD3/ CD56+CD16. Donor cell microchimerism was studied using semi-quantitative polymerase chain reaction Y-chromosome detection in female infants who received male donor blood. Donor and recipient HLA class II typing was performed with polymerase chain reaction with sequence specific primers. RESULTS: The lymphocyte counts in both groups were significantly increased after transfusion, and there was a significant increase in lymphocytes expressing CD45RA, CD3-/CD16+CD56, CD80, and CD3-/DR on Day 14. The premature infants' pretransfusion natural killer cell population (CD3-ICD16+CD56) was significantly lower than that of term infants, but it reached a similar level by Days 10-14. CD8 subpopulations were increased but not CD4+ cells. Two female infants (of 6) had circulating Y chromosomes 1 day after transfusion, and most of the infants effectively cleared the donor cells within 24 hours of transfusion. Two Group 2 infants who by chance received presumably HLA-haploidentical donor blood developed necrotizing enterocolitis. CONCLUSION: Blood transfusion alters immune cell antigen expression in premature neonates and may initially be immunostimulatory and later immunosuppressive.