Variation in immunoglobulin levels and circulating immune complexes in sarcoidosis. Correlation with extent of disease and duration of symptoms.

Sixty-three patients with clinically definite sarcoidosis confirmed histologically and/or by a positive Kveim test were studied according to the clinical and radiographic extent and known duration of their disease and symptoms. Immunoglobulin levels were not raised among patients with bilateral hilar lymphadenopathy (BHL) alone, but IgG and IgA were raised among patients with pulmonary sarcoidosis, most markedly among patients with long-standing active disease. Serum IgM was found elevated in extrathoracic sarcoidosis. West Indian males had the highest levels of IgG. The presence of circulating immune complexes reacting with conglutinin was strongly associated with a recent symptomatic onset of sarcoidosis; they were more prevalent in patients with BHL and erythema nodosum. In contrast, polyethylene glycol precipitable immunoglobulins were associated with long-standing active disease and with neurologic involvement.