Proof of concept that most borderline Quantiferon results are true antigen-specific responses

What is it about?

Quantiferon is a blood test which is used when infection with the tuberculosis bacillus is suspected. This test is very specific, i.e. will only be positive when there really is an infection. When the test is above a certain value (‘cut-off’) the test result is positive, if below the value the result is negative. In the present study three findings showed that most test results just below the cut-off (borderline results), thus officially negative, were in fact real responses to the tuberculosis bacillus. First, such borderline results occurred more often than explained by chance. Secondly, patients with borderline results were not different from those with positive results in almost all respects. What these findings mean for the patients must now be studied. We think that it may be especially important for patients with decreased immunity.

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