Background. We determined the consistency of positive interferon-gamma (IFN-γ) release assays (IGRAs) to detect latent TB infection (LTBI) over one-year postpartum in HIV-1-infected women. Methods. Women with positive IGRAs during pregnancy had four 3-monthly postpartum IGRAs. Postpartum change in magnitude of IFN-γ response was determined using linear mixed models. Results. Among 18 women with positive pregnancy IGRA, 15 (83%) had a subsequent positive IGRA; 9 (50%) were always positive, 3 (17%) were always negative, and 6 (33%) fluctuated between positive and negative IGRAs. Women with pregnancy IGRA IFN-γ spot forming cells (SFCs)/well were more likely to have consistent postpartum IGRA response (odds ratio: 10.0; 95% confidence interval (CI): 0.9–117.0). Change in IFN-γ response over postpartum was 10.2 SFCs/well (95% CI: ？1.5–21.8 SFCs/well). Conclusion. Pregnancy positive IGRAs were often maintained postpartum with increased consistency in women with higher baseline responses. There were modest increases in magnitude of IGRA responses postpartum. 1. Background Tuberculosis (TB) and human immunodeficiency virus type 1 (HIV-1) infection are major health problems in women, particularly during their reproductive years (15–49) [1]. In a recent analysis, we observed that HIV-1-infected women with latent TB infection (LTBI) as detected by a positive interferon-gamma (IFN-γ) release assay (IGRA) during pregnancy are at increased risk of active TB during the postpartum period [2]. Postpartum active TB is associated with increased risk of mortality in HIV-1-infected women and their infants and is also associated with an increased risk of HIV-1 transmission to the infants [3, 4]. Thus, IGRAs during or after pregnancy may be useful in identifying women at increased risk for future active TB who in turn may expose their infants. LTBI has traditionally been detected using the tuberculin skin test (TST), which has limitations in specificity due to cross-reactivity with bacille Calmette-Guerin (BCG) vaccine and in sensitivity due to anergy in immunocompromised and malnourished individuals [5]. In contrast, IGRAs are not confounded by prior BCG, correlate better with exposure to active TB than TST, and are not prone to boosting on repeat testing [5–8]. IGRAs measure immune responses to MTB antigens: early secretory antigenic target 6-kD protein (ESAT-6) and culture filtrate protein 10 (CFP-10). While there are data on IGRA performance following known recent TB exposure or in presence of active TB, little is known regarding variability of IGRA responses among
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