Interferon-γ and skin test responses of schoolchildren in southeast England to purified protein derivatives from Mycobacterium tuberculosis and other species of mycobacteria

Abstract

SUMMARY The immune responses of schoolchildren in southeast England to Mycobacterium tuberculosis and other species of mycobacteria were studied prior to vaccination with bacille Calmette-Guérin (BCG). Data are presented for tuberculin (Heaf) skin test and interferon-γ (IFN-γ) responses to M. tuberculosis purified protein derivative (PPD), and IFN-γ responses to PPDs from eight other environmental mycobacteria, measured in 424 schoolchildren (13–15 years of age). Responses to M. tuberculosis PPD were detected in 27% of schoolchildren by in vitro IFN-γ response and in 20% by the Heaf test. IFN-γ responses were more prevalent to PPDs from species of mycobacteria other than M. tuberculosis, predominantly those of the MAIS complex and M. marinum (45–60% responders). Heaf test and IFN-γ responses were associated (P < 0·001) for M. tuberculosis, MAIS and M. marinum. These findings have implications for appropriate implementation of vaccination against tuberculosis.