C3b receptor-mediated phagocytosis in sarcoidosis with extra-thoracic manifestations

Two groups of sarcoidosis patients were studied. One group of 24 patients had previously had erythema nodosum (EN+), and the other group of 54 patients had never had any such extrathoracic manifestation of the disease (EN-). The two groups were similar with respect to age, disease duration, chest radiographic appearance, and granuloma mass as estimated from the serum concentration of lysozyme. Neutrophil phagocytic function was studied by a kinetic method which allows distinction between Fc- and C3b-receptor-mediated uptake. Fc-receptor function was normal in both groups. The function of C3b receptors was normal in the EN+ groups but significantly reduced in the EN- group. This observation indicates that sarcoidosis associated with erythema nodosum may represent a separate disease entity with respect to the pathogenetic mechanism involved in granuloma formation.