Growth Inhibition Assay of Human Alveolar Macrophages as a Correlate of Immune Protection Following Mycobacterium bovis Bacille Calmette-Guérin Vaccination.

Background: In order to eliminate tuberculosis (TB), an effective vaccine is urgently needed to prevent infection with . A key obstacle for the development of novel TB vaccines is the lack of surrogate markers for immune protection against .

Methods: We investigated growth rates of in the mycobacterial growth inhibition assay (MGIA) as a marker for mycobacterial growth control of human bronchoalveolar lavage (BALC) and peripheral blood mononuclear cells (PBMC) before and after vaccination with Bacille Calmette-Guérin (BCG) of healthy adult volunteers.

Results: Vaccination induced a positive response ( < 0.001) to purified protein derivate (PPD) in 58.8% of the individuals in an interferon-γ release assay-ELISpot. Intraindividual evaluation of the MGIA growth rates before and after BCG-vaccination revealed no significant difference in time to culture positivity before and after vaccination in BALC ( = 0.604) and PBMC ( = 0.199). The magnitude of the PPD-response induced by BCG-vaccination did not correlate with growth control in BALC and PBMC (correlation = 0.468, 95% CI: -0.016 to 0.775).

Conclusion: In conclusion, BCG-vaccination-induced mycobacterial-specific cytokine immune response does not result in functional immune control against in the MGIA.