1645. Factors Associated with Extremely High Response of T-SPOT.TB in Patients with Extrapulmonary Tuberculosis
Session: Poster Abstract Session: Mycobacterial Infections
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C

Background: T-SPOT.TB, a recently developed T-cell based assay, has shown promising results in diagnosing tuberculosis (TB). It is hypothesized that the magnitude of response to early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10), which are encoded by genes in the region of difference-1 (RD-1), is influenced by difference of disease status or host condition. Although strong responses of T-SPOT.TB occasionally occur, limited data are available on which factors are associated with these strong immunologic responses. We thus investigated the factors associated with extremely high response of T-SPOT.TB in patients with extrapulmonary TB (E-TB).

Methods: Between April 2008 and November 2012, adult patients with suspected E-TB were prospectively enrolled at a tertiary hospital in an intermediate TB-burden country. Patients with extremely high response of T-SPOT.TB, defined as results of >= 1000 spot forming units (SFU)/2.5 x105 PBMC to ESAT-6 or CFP-10, were compared with control patients with low response of T-SPOT.TB, <= 99 SFU (6-99 SFU)/2.5 x 105 PBMC to ESAT-6 or CFP-10.

Results: Of the 350 patients with suspected E-TB, 208 (59%) patients with 153 (74%) confirmed and 55 (26%) probable E-TB were included in this study. Of these 208, 173 (49%) patients showed positive results of T-SPOT.TB. Of these 173 patients, 26 (15%), 76 (44%), and 71 (41%) revealed >= 1000 SFU, 100-999 SFU, and 6-99 SFU/2.5 x 105 PBMC to RD-1 in T-SPOT.TB assay, respectively. Thus, 26 (15%) patients with extremely high response and 71 (41%) with low response were finally included for further analysis. Univariate and multivariate analyses are shown in Table 1. Univariate analysis revealed that young age, confirmed TB, and miliary TB were significantly associated with extremely high response results of T-SPOT.TB. In a multivariate analysis, miliary TB (OR=14.5; 95% CI 3.9-53.8) was significantly associated with extremely high response results of T-SPOT.TB, while advanced age (OR=0.9; 95% CI 0.9-1.0), and immunosuppression (OR=0.2; 95% CI 0.02-0.9) was associated with low response T-SPOT.TB results.

Conclusion: Our data suggest that mycobacterial burden and host immune status may contribute to the strong responsiveness of T-SPOT.TB assay. 


Yu-Mi Lee, MD1,2, Sun-Mi Kim, PhD1, Su Jin Park, PhD1, Sang-Oh Lee, MD1, Sang-Ho Choi, MD1, Yang Soo Kim, MD1, Jun Hee Woo, MD, PhD1 and Sung-Han Kim, MD1, (1)Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea, (2)Department of Infectious Diseases, Busan Paik Hospital, Inje University College of Medicine, Busan, South Korea

Disclosures:

Y. M. Lee, None

S. M. Kim, None

S. J. Park, None

S. O. Lee, None

S. H. Choi, None

Y. S. Kim, None

J. H. Woo, None

S. H. Kim, None

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