Clinical and laboratory factors contributing to uninterpretable beryllium lymphocyte proliferation tests (BeLPT).

BACKGROUND: The beryllium lymphocyte proliferation test (BeLPT), has become the principal clinical test for detecting beryllium sensitization and chronic beryllium disease. Uninterpretable BeLPT results can occur in a small but significant proportion of tests from poor lymphocyte growth (PG) or over proliferation of lymphocytes (OP). The clinical and laboratory causes of uninterpretable results are not known. METHODS: BeLPT data from the US Department of Energy-supported Former Worker Screening Program were analyzed for a 10-year period. Drivers of uninterpretable BeLPTs were investigated using multivariable models and classification techniques. RESULTS: Three participant attributes were significantly associated with PG, while OP showed no significant associations. Serum lot for the lymphocyte growth medium accounted for 21% of the variation in PG and 16% in OP. CONCLUSION: Serum lots influence the likelihood of having uninterpretable BeLPT. To better understand uninterpretable results and possibly reduce their occurrence, additional laboratory-related factors should be addressed.

The beryllium lymphocyte proliferation test: Relevant issues in beryllium health surveillance.

BACKGROUND: The beryllium lymphocyte proliferation test (Be-LPT) measures beryllium-specific cellular immune response, and is useful in medical surveillance of beryllium sensitivity and chronic beryllium disease (CBD). METHODS: Current and former employees (n = 12,194) of 18 United States Department of Energy (DOE) sites were tested for beryllium sensitization at four laboratories with Be-LPT expertise. Beryllium sensitized individuals were offered evaluations for CBD. The sensitivity, specificity, and positive predictive value (PPV) of the Be-LPT were determined, as was inter- and intra-laboratory agreement. RESULTS: False positives were calculated to be 1.09%, with a laboratory range of 0.00-3.35% for the 10-year investigation. Be-LPTs performed on inter-laboratory split blood specimens from sensitized individuals showed a false negative rate of 31.7%. The intra-laboratory repeatability of abnormal Be-LPT results ranged from 80.4-91.9%. The sensitivity of the Be-LPT was determined to be 0.683, with a specificity of 0.969. The PPV of one abnormal Be-LPT was 0.253. CONCLUSIONS: The Be-LPT is efficacious in medical surveillance of beryllium-exposed individuals. The PPV of the Be-LPT is comparable to other widely accepted medical tests. Confirmation of an abnormal result is recommended to assure appropriate referral for CBD medical evaluation.