Abstract
Purpose::
Tuberculose skin test (PPD) has limited power for diagnosing tuberculosis since active disease cannot be differentiated from immunity. Therefore, we evaluated the usefulness of a whole-blood interferon-γ enzyme-linked immunosorbent assay (QuantiFERON TB-2G [QFT]; Cellestis) in obtaining a diagnosis of tuberculosis in patients with uveitis (TB).
Methods::
QFT-G is a whole blood, antigen-specific, test that utilizes synthetic peptides representing two M. tuberculosis proteins, ESAT-6 and CFP-10. After incubation for 16 to 24 hours, the amount of interferon-γ secreted by monocytes in response to these antigens is measured. We used the test in 34 uveitis patients in which tuberculosis was included in the differential diagnosis. These were patients with either active granulomatous uveitis unresponsive to topical or systemic corticosteroid therapy (n = 12), or inactive posterior uveitis with a serpiginous/multifocal chorioiditis (MCP)-like presentation (n = 15), or posterior uveitis with different clinical pictures (n = 6). These rates were compared to a group of healty hospital personel.
Results::
15/34 patients (44%) were tested positive. Of the patients with active inflammatory disease 4 were tested positive (33%). 60% (9/15) of our patients with inactive, posterior, serpiginous like uveitis were tested QFT-positive. Only 1 patient (17%) of the patients with posterior uveitis of different presentation was QFT positive. The rate of QFT-positivity in the healthy control group (n = 208) was 6%.
Conclusions::
TB-uveitis seems to present in two forms: active granulomatous disease and inactive disease with chorioretinal scarring like serpiginous choroiditis or MCP. Admitting patients with the latter form to QFT testing increases the post-test-probability of TB. QFT testing seems to be a useful test in the differential diagnosis of tuberculous uveitis.
Keywords: uveitis-clinical/animal model • inflammation • chorioretinitis