Alternative screening assay to beryllium lymphocyte proliferation test for identification of beryllium sensitization – Pilot study

Abstract

Sarcoidosis is a rare interstitial lung disorder of unknown aetiology. In contrast, chronic beryllium disease (CBD), which is clinically indistinguishable from sarcoidosis, is induced by occupational beryllium exposure. In both disorders the primarily affected organ is the lung. The only applicable hallmark to differentiate sarcoidosis from CBD is the presence of beryllium specific T cells defined as beryllium sensitization (BeS) which is a prerequisite for clinical manifestation of CBD. To date the only assay to detect BeS is the beryllium lymphocyte proliferation test (Be-LPT) which measures the capability of T cell lymphocytes in peripheral blood or bronchoalveolar lavage to proliferate ex-vivo in response to beryllium. Since this cumbersome Be-LPT harbours a huge number of technical parameters critical for the final result interpretation the Be-LPT is performed only in a limited number of expert laboratories world wide. We think a robust, cheap and simple assay for detection of BeS is needed to cover the increasing demand for appropriate occupational surveillance in referring occupational settings. To develop an alternative assay we measured beryllium induced IFN-gamma concentrations in supernatants of cultivated peripheral blood cells of beryllium exposed and unexposed individuals after defined time intervals and compared the results with those of simultaneously performed Be-LPTs. Up to date we included 37 assays which had been performed at two independent laboratories in Borstel and Freiburg following an identical work flow. Simultaneous performance of the alternative assay and the Be-LPT revealed consistent findings 76.9%. To date 23.1% of the findings differed between the tests compared. Of interest is the result that individuals with a positive Be-LPT show significantly increased IFN-gamma levels compared with those with a negative finding. This was true for all Beryllium concentrations included and time intervals tested. In conclusion the data presented in this pilot study are promising. However, the numbers of tests have to be increased significantly to improve the statistical power of this study.