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Published on: August 30, 2014
Delayed-type hypersensitivity, mycobacterial vaccines and protective immunity
P E Fine1, J A Sterne, J M Pönnighaus
1Department of Epidemiology and Population Sciences, London School of Hygiene and Tropical Medicine, UK.
Lancet (London, England)
|November 5, 1994
Summary
Delayed-type hypersensitivity to mycobacterial antigens offers protection against leprosy, but not tuberculosis. Low-level sensitivity may indicate environmental exposure and protection, while persistent vaccine-induced hypersensitivity does not correlate with BCG vaccine efficacy.
Area of Science:
- Immunology
- Infectious Diseases
- Vaccinology
Background:
- The role of delayed-type hypersensitivity in immunity to mycobacterial infections remains debated.
- Understanding correlates of vaccine-induced immunity is crucial for improving vaccines like BCG.
- BCG vaccine efficacy varies significantly across populations.
Purpose of the Study:
- To investigate the implications of delayed-type hypersensitivity for protection against tuberculosis and leprosy.
- To identify correlates of vaccine-induced protective immunity against mycobacterial diseases.
- To clarify the relationship between hypersensitivity and BCG vaccine effectiveness.
Main Methods:
- A large-scale prospective study involving over 70,000 individuals in Malawi.
- Skin testing with mycobacterial antigens (tuberculin and leprosy bacilli antigens).
- Five-year follow-up for tuberculosis and leprosy incidence, with analysis of incidence rate ratios adjusted for covariates.
Main Results:
- BCG vaccination provided protection against leprosy independent of delayed-type hypersensitivity.
- In unvaccinated individuals, hypersensitivity to mycobacterial antigens was linked to strong protection against leprosy.
- A J-shaped relationship was observed between tuberculin hypersensitivity and tuberculosis rates, with low-grade sensitivity associated with the lowest incidence.
Conclusions:
- Delayed-type hypersensitivity has differential implications for tuberculosis and leprosy.
- Low-level hypersensitivity, potentially from environmental mycobacteria, is associated with protection.
- Persistent vaccine-induced hypersensitivity is not a reliable correlate of BCG-induced protection against mycobacterial diseases.
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