High incidence of maternal HLA A, B and C antibodies associated with a mild course of haemolytic disease of the newborn

Mild courses of haemolytic disease of the foetus or newborn (HDN) due to Rh (D) blood group antibodies are associated with and may therefore be amelio rated by maternal antibodies reacting with human leucocyte antigens (HLA) o f the child, an observation drawn from our own earlier data (Neppert J, Kis sel K. Lancet 1992;339:1481). This study (i) corroborates this association; (ii) reveals shortcomings in the published data; and (iii) examines the ch aracteristics of HDN cases when these shortcomings have been rectified. Sam ples from 51 women with antibodies against their child's blood group antige ns of the Rh system were analysed for HLA A, B, C and DR antibodies during parturition. The mothers were divided into two groups, either severe or mil d, dependent upon the clinical course of the HDN, and the incidence of HLA antibody production was determined for each group. HLA A, B, C and/or DR an tibodies were detected in 85.2% of those women whose children had a mild co urse of HDN prenatally or perinatally (n = 27). This is statistically great er than the incidence of 50.0% (Fisher's exact test: p = 0.014) found in th e group of women whose children had a severe HDN either pre- or perinatally (n = 24) and is greater than the 35% (n = 20; p = 0.0001) found in women w ithout Rh or other irregular antibodies. HLA DR antibodies were detected in three cases. The findings support our hypothesis that maternal anti HLA. A , B and C antibodies may protect against a potential severe HDN. We therefo re assume that those women will benefit who have already had a child with a severe HDN and in whom HLA antibodies were not previously detected, if HLA antibody production is provoked by subcutaneously inoculating with the fat her's leucocytes before or at the beginning of the new pregnancy.