Association between tuberculosis and atopy: role of the CD14-159C/T polymorphism

Abstract

Background: The development of allergic hypersensitivity depends on both genetic and environmental factors. Different amounts of microbial products could affect patients with atopy and different genotypes.

Objective: We aimed to evaluate the role of varying degrees of exposure to infection by Mycobacterium tuberculosis (tuberculosis) in atopic patients and analyze the association with genetic factors.

Methods: We performed CD14-159C/T genotyping in atopic patients (n=118) and healthy individuals (n=62) and recorded the following variables: rural lifestyle, exposure to persons with tuberculosis, bacille Calmette-Guerin (BCG) vaccination, tuberculin skin test (TST), skin prick test, and phenotypes of atopy. Blood samples were analyzed for soluble-CD14 (sCD14), interferon (IFN) y, total immunoglobulin (Ig) E, and eosinophil levels. A score was used to identify the likelihood of exposure to tuberculosis.

Results: Almost all the study participants had had a BCG vaccination, and half had a positive TST result. No differences were observed between atopic patients with high/low tuberculosis scores and CD14 genotypes in terms of atopic phenotypes, allergen sensitization, and levels of total IgE, sCD14, and IFN-y. However, the frequency of asthma was higher in atopic patients with a high tuberculosis score and was not associated with CD14 genotypes. Eosinophil counts in blood were higher in atopic patients with a high tuberculosis score and CC+CT genotypes.

Conclusions: These results suggest that the C allele of the CD14-159C/T polymorphism has a marked effect on eosinophil levels in atopic patients with increased exposure to tuberculosis. In addition, the degree of exposure to tuberculosis in atopic patients may modify the development of asthma.