Revisiting the Heterogeneous IFN-γ Response of Bacille of Calmette-Guérin (BCG)-Revaccinated Healthy Volunteers in a Randomized Controlled Trial: Effect of the Body Mass Index and of the IFNG+874 A/T Polymorphism.

In trials evaluating the immune responses to Bacille of Calmette-Guérin (BCG), the genetic background and the nutritional status are host-related factors that could affect the heterogeneity in these parameters. The IFNG+874 A/T (rs 62559044) polymorphism has been reported to influence the IFN-γ production by BCG-vaccinated individuals challenged in vitro with mycobacterial antigens. The body mass index (BMI) is a proxy for the nutritional status and has been associated both with the susceptibility to tuberculosis and with the IFN-γ response. We show that although the IFNG+874 A/T polymorphism was not associated with the heterogeneity of IFN-γ production in a randomized controlled trial that evaluated long-term immune responses to BCG revaccination previously conducted in Salvador, Bahia, Brazil, the effect of this polymorphism on the observed increase in IFN-γ production among revaccinated subjects was adjusted in individuals with a low BMI.