Subacute (de Quervain's) thyroiditis: association with HLA-Bw35 antigen and abnormalities of the complement system, immunoglobulins and other serum proteins.

The HLA antigens in 40 patients with subacute thyroiditis were investigated. An association between subacute thyroiditis and HLA-Bw35 antigen as previously reported, was confirmed. Further immunological observations included a decrease in Serum Clq, C4 and C3 activator levels; conversely, there was an increase in serum C3, IgM, alpha1-acid glycoprotein and alpha1-antitrypsin levels. Serum IgA levels were decreased in those patients who were Bw35 negative, but were normal in the patients who were Bw-35 positive, with serum alpha2-macroglobulin levels the opposite was found. These studies support the view that a genetic factor(s), viz., the major histocompatibility system, plays a role in the pathogenesis of subacute thyroiditis. A "nosological clustering" around the Bw35 antigen as a marker for viral susceptibility is suggested.