Pulmonary immunologic features of alveolar septal amyloidosis associated with multiple myeloma.

A 74-year-old man presented with interstitial pulmonary disease which was proven to be alveolar septal amyloidosis by transbronchial biopsy. Multiple myeloma was diagnosed on the basis of monoclonal IgG-lambda protein in serum, monoclonal lambda light chains in urine, a bone marrow plasmacytosis of 22 percent, and serum IgA and IgM levels less than 100 mg/dl and 50 mg/dl, respectively. Appropriate investigations failed to show additional sites of deposition of amyloid. Analysis of fluid from bronchoalveolar lavage showed an increase in total cells recovered, a lymphocytosis with a ratio of T helper over T suppressor cells greater than that in peripheral blood, the presence of an IgG-lambda paraprotein, and an IgG/albumin ratio greater than that in serum. While plasma cells could not be identified in the recovered cell population, cultured cells from bronchoalveolar lavage fluid showed increased production of IgG. These findings provide evidence of an ongoing pulmonary immune response resulting in excess IgG-lambda protein in the pulmonary compartment, a factor which may contribute to the development of amyloidosis.