Chronic beryllium disease: a hypersensitivity disorder.

Chronic beryllium disease (CBD) is one of two pulmonary syndromes caused by environmental exposure to beryllium. Acute beryllium disease was first described in 1943 and is an acute toxic reaction to beryllium. CBD was first described in 1946 and the pathogenesis of this disorder was not fully appreciated until the development of fiberoptic bronchoscopy allowed sampling of bronchoalveolar lung cells. Because CBD was associated with a delayed skin test reaction to beryllium, occurred in only 1-5 percent of individuals, was not associated with a clear-cut dose-response curve, and was associated with a granulomatous reaction, a hypersensitivity to beryllium was suspected as the cause. The hypothesis that CBD was due to hypersensitivity was not proven until the 1980s when samples of bronchoalveolar cells obtained by bronchoscopy demonstrated that not only did every individual with CBD have lymphocytes that could respond to beryllium (lymphocyte proliferation assay), but, also, that there was an accumulation of these cells at the site of active disease. The immunological reaction in CBD was associated with CD4+ lymphocytes responding to a beryllium-influenced but unknown peptide(s) that was (were) presented by HLA molecules on antigen-presenting cells. Genetic studies also demonstrated an association of CBD with HLA-DPB1 alleles that contain glutamine at position 69 in up to 97 percent of subjects with CBD but also 30-40 percent of controls. The understanding that CBD is a hypersensitivity disorder has had important implications for the diagnosis, screening, and environmental control precautions necessary for its prevention.