HNA specificity and association to HLA-DRB1 and -DQB1 in patients with autoimmune neutropenia of early childhood

Autoimmune neutropenia (AIN) of early childhood is caused by autoantibodies against antigens on the neutrophil membrane. Human leukocyte antigens (HLA) have previously been associated with AIN. This study investigated HLA-DRB1 and HLA-DQB1 alleles in 160 antibody positive patients and compared with 1000 controls. Increased risk was observed for DRB1*10, DRB1*14, DRB1*16 and DQB1*05, and lower risk for DRB1*04, DRB1*13 and DQB1*03. Haplotypes with higher risk included: DRB1*10/DQB1*05, DRB1*14/DQB1*05 and DRB1*16/DQB1*05, while DRB1*04/DQB1*03, DRB1*07/DQB1*02, and DRB1*13/DQB1*06 were associated with lower risk. Associated HLA-DRB1 and –DQB1 differed between patients positive for anti-HNA-1a-specific antibodies and patients positive for broad reactive anti-FcγRIIIb antibodies. DRB1*01, DRB1*04 and DQB1*03 was only associated for anti-HNA-1a positive, and DRB1*10 was restricted to broad reactive anti-FcγRIIIb positive. Strong association between AIN and HLA-DRB1 and -DQB1 alleles and haplotypes suggested that they play a role in susceptibility or protection. Different associations regarding FcγRIIIb antibody specificities could indicate disease heterogeneity.