[Neonatal thrombopenia caused by antiPLA1 and HLA-DR3 antigen alloimmunization].

The HLA typing of mothers alloimmunised against the PLA1 antigen of their thrombocytopenic neonate shows that the A1, B8, DR3 haplotype is involved. The very strong association found with DR3 (20/21) suggests that an immune response gene located in the D region of the major histocompatibility complex might be responsible for the ability to develop an anti PLA1 antibody.