Bucillamine induced pulmonary injury occurs with immunoglobulin decrease.

We describe pulmonary involvement in 3 patients with rheumatoid arthritis treated with bucillamine. In all 3, synovitis was in remission. The common radiological characteristic was mottled dense infiltrates, in which were air bronchograms, in the bilateral central lung, sparing the periphery. Lung biopsies in 2 cases revealed organizing exudates in the alveolar ducts and alveoli, and cellular infiltration into alveoli and septa. Serum immunoglobulin (Ig) levels decreased markedly at the time of involvement. After discontinuation of bucillamine, lung injury resolved without exacerbation of synovitis and Ig levels increased. A mechanism involving decreased Ig concentration is suggested.