LUPUS ANTICOAGULANTS - STRONG ASSOCIATION WITH THE MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-II AND PLATELET ANTIBODIES

A relationship between the presence of platelet autoantibodies and maj or histocompatibility complex class II alleles was determined in 27 pa tients with lupus anticoagulants. Twenty-two patients had a 'primary a ntiphospholipid syndrome' and five patients had lupus erythematosus (S LE). Platelet antibodies against the platelet glycoproteins (GP) IIb/I IIa were detectable in 20 patients. Anti-GPIb/IX or -GPIV antibodies w ere detectable only in patients with anti-GPIIb/IIIa antibodies. An in creased frequency of HLA-DQB106 was demonstrable in the total patient population. The association between the lupus anticoagulants and HLA- DQB106 was even stronger if patients also had detectable platelet ant ibodies. This association was also seen if patients with a history of thromboembolic disease were considered separately. However, within the patient population there was no difference between frequencies of HLA alleles detectable platelet antibodies.