Identification of a major locus, TNF1, that controls BCG-triggered tumor necrosis factor production by leukocytes in an area hyperendemic for tuberculosis

Abstract

Background. Tumor necrosis factor (TNF) is a key immune regulator of tuberculosis resistance, as exemplified by the highly increased risk of tuberculosis disease among individuals receiving TNF-blocker therapy. Methods. We determined the extent of TNF production after stimulation with BCG or BCG plus interferon gamma (IFN-γ) using a whole blood assay in 392 children belonging to 135 nuclear families from an area hyperendemic for tuberculosis in South Africa.We conducted classical univariate and bivariate genome-wide linkage analysis of TNF production using the data from both stimulation protocols by means of an extension of the maximum-likelihoodbinomial method for quantitative trait loci to multivariate analysis. Results. Stimulation of whole blood by either BCG or BCG plus IFN-γ resulted in a range of TNF release across subjects. Extent of TNF production following both stimulation protocols was highly correlated (r = 0.81).We failed to identify genetic linkage of TNF release when considering each stimulus separately. However, using a multivariate approach, we detected a major pleiotropic locus (P < 10-5) on chromosome region 11p15, termed TNF locus 1 (TNF1), that controlled TNF production after stimulation by both BCG alone and BCG plus IFN-γ. Conclusions. The TNF1 locus was mapped in the vicinity of the TST1 locus, previously identified in the same family sample, that controls tuberculin skin test (TST) negativity per se, that is, T-cell-independent resistance to Mycobacterium tuberculosis infection. This suggested that there is a connection between TST negativity per se and TNF production. © The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved.