1344. Interferon Gamma Release Assay (IGRA) Responses in HIV-Infected and -Uninfected Women in Pregnancy

Abstract

Background. Pregnancy and HIV-associated immunologic changes may affect latent TB infection (LTBI) interferon-gamma release assay (IGRA) QuantiFERON TB Gold Plus (QFT-Plus) diagnostic performance. Methods. In this ongoing study, HIV-infected and -uninfected women 20-34 weeks gestation without TB in the past year are enrolled from antenatal clinics in western Kenya and tested with QFT-Plus. Mean quantitative IFN- γ responses to mitogen, and M. tuberculosis antigens (TB1 [primarily CD4+] and TB2 [addition of CD8+ response]) were compared using two-sample t-tests. Proportions for categorical variables were compared using univariate logistic regression. Results. Among 306 women (HIV+ 127 [41.5%], HIV- 179 [58.5%]) enrolled between January 2018 and March 2019, median maternal and gestational age were 25 years (IQR 21-28) and 28 weeks (IQR 24-32), respectively. Among HIV-infected women at enrollment, 99.2% were on ART, median CD4 count was 440 cells/mm3 (IQR 235-703), 37.5% were virally suppressed, and 60.6% reported having received isoniazid preventive therapy (IPT). Overall, 95 (31.1%) women were QFT-Plus positive (HIV+ 38 [29.9%], HIV- 57 [31.8%], OR 0.90, 95% CI 0.54-1.48, P = 0.671); 190 (62.1%) were negative (HIV+ 81 [63.8%], HIV- 109 [60.9%]), and 21 had indeterminate results (HIV+ 8 [6.3%], HIV- 13 [7.3%], OR 0.83, 95% CI 0.33-2.09, P = 0.690). Mean response to mitogen was similar between HIV-infected and -uninfected women (6.0 vs. 6.1 IU/mL, P = 0.663]. Among QFT-Plus positive women, HIV+ women had significantly lower TB1 responses than HIV- women (HIV+ 2.7 vs. 4.2 IU/mL, P = 0.035). Mean TB2 responses had a similar pattern, but did not reach statistical significance (HIV+ 3.1 vs. 4.3 IU/mL, P = 0.107). Both TB1 and TB2 were positive for 82 women (86.3%), 4 women were only TB1 positive (4.2%), and 8 women were only TB2 positive (8.4%). Conclusion. Among pregnant women, HIV-infection was not associated with increased prevalence of QFT+ responses. However, among QFT-positive women, TB1 responses were lower in HIV-positive women with a similar trend observed for TB2 responses. These findings suggest that HIV-associated immunologic changes may influence QFT test performance.