Evaluation of the quality of HLA antibodies in placental blood.

Two groups of blood samples, placental blood and female donor blood, were shown to have a frequency of 16.4 and 1.5% of anti-human leucocyte antigen (HLA) antibodies respectively. The specificities and qualities of these antibodies were further characterized by their relative coefficient (r) values and strength indices (SIs). Most had an r value of approximately one, but their SIs varied from 41 to 100%. Among these two groups, nine samples gave very strong and definite results (r = 1 and SI = 100%). Data analysis revealed that the qualities of the two groups were comparable. However, the antibody positive rate was higher in placental blood samples than that in donor blood samples.