Summary auto-generated
This study evaluated a total blood lymphocyte proliferation (TLP) assay as a screening test for Mycobacterium tuberculosis infection and compared it with the tuberculin skin test. Researchers tested 33 tuberculosis patients and 37 non-tuberculous control subjects using a simplified TLP method that requires only 100 microliters of whole blood obtained by fingerprick. The TLP assay measures lymphocyte proliferation in response to tuberculin purified protein derivative (PPD) using radioactive thymidine incorporation. Results showed a highly significant correlation between TLP responses and skin test responses, with odds ratios of 8.5 in patients and 12.0 in controls. Both tests demonstrated similar sensitivity, specificity, and positive predictive values (approximately 58-64%). The authors conclude that the TLP test is as effective as tuberculin skin testing for screening tuberculosis infection, with potential advantages including requiring only fingerprick blood samples and eliminating the need for patient return visits. They suggest future improvements could lead to the TLP assay replacing intradermal skin testing.
Key findings
- Significant correlation between TLP assay responses and tuberculin skin test responses in both tuberculosis patients and controls
- Similar sensitivity, specificity, and positive predictive values (~58-64%) for both TLP and skin tests in distinguishing tuberculosis cases from non-tuberculous disease
- TLP assay requires only 100 microliters of whole blood via fingerprick and does not require patient return visits for result reading
- TLP test performance is comparable to tuberculin skin testing but with practical advantages for screening tuberculosis infection
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Abstract
The total blood lymphocyte proliferation assay (TLP) was evaluated as a screening test for infection with Mycobacterium tuberculosis and was compared with the tuberculin (Mantoux) skin test. The results of TLP assays performed on 33 patients with tuberculosis and 37 non-tuberculous subjects were compared with results of skin tests performed in the previous year. There was a high correlation between skin test responses and TLP responses to PPD which was statistically significant. The sensitivity, specificity and the predictive value of a positive test were also similar for the skin test and TLP test. These findings suggest that the TLP test is as effective in screening for M. tuberculosis infection as tuberculin skin testing. Future research leading to further simplification of the TLP method may lead to it replacing intradermal skin testing.