Flow cytometric test for beryllium sensitivity

Abstract

Background Chronic beryllium disease (CBD) is an occupational granulomatous disorder characterized by hypersensitivity to beryllium, mediated by CD4⁺ T lymphocytes, and predominantly affects the lungs. In this disorder, lymphocyte proliferative responses to beryllium, measured by ³H thymidine incorporation, are used for diagnosis of CBD, for screening asymptomatic workers or former workers to detect unrecognized disease, and for surveillance as a bioassay to detect abnormal exposures. Problems with test variability and the use of radioactivity have recently led to the search for alternative methods. Methods We applied a 5,6‐carboxyfluorescein diacetate succinimidyl ester flow cytometric technique for measurement of mitogen‐ and antigen‐induced T‐lymphocyte proliferation to a group of beryllium‐exposed sensitized individuals and beryllium‐unexposed controls. Results We detected mitogen and antigen proliferative responses in CD3⁺, CD4⁺, and CD8⁺ subpopulations. Phytohemagglutinin and Candida stimulated CD4⁺ and CD8⁺ T‐cell responses, but beryllium appeared to stimulate only CD3⁺/CD4⁺ responses. Conclusions This technique may provide a sensitive, nonradioactive alternative to the traditional proliferation tests that measure beryllium sensitivity. It offers the added specificity of enabling phenotypic description of the responding cell type and may prove to be easier to standardize for clinical use.