Gamma-irradiated Bacille calmette-guérin vaccination does not modulate the innate immune response during experimental human endotoxemia in adult males

Bacille calmette-guérin (bcg) vaccine exerts nonspecific immunostimulatory effects and may therefore represent a novel therapeutic option to treat sepsis-induced immunoparalysis. we investigated whether bcg vaccination modulates the systemic innate immune response in humans in vivo during experimental endotoxemia. we used inactivated gamma-irradiated bcg vaccine because of the potential risk of disseminated disease with the live vaccine in immunoparalyzed patients. in a randomized double-blind placebo-controlled study,healthy male volunteers were vaccinated with gamma-irradiated bcg (n=10) or placebo (n=10) and received 1 ng/kg lipopolysaccharide (lps) intravenously on day 5 after vaccination to assess the in vivo immune response. peripheral blood mononuclear cells were stimulated with various related and unrelated pathogens 5,8 to 10,and 25 to 35 days after vaccination to assess ex vivo immune responses. bcg vaccination resulted in a scar in 90% of vaccinated subjects. lps administration elicited a profound systemic immune response,characterized by increased levels of pro- and anti-inflammatory cytokines,hemodynamic changes,and flu-like symptoms. however,bcg modulated neither this in vivo immune response,nor ex vivo leukocyte responses at any time point. in conclusion,gamma-irradiated bcg is unlikely to represent an effective treatment option to restore immunocompetence in patients with sepsis-induced immunoparalysis. this trial is registered with nct02085590. © 2015 linda a. c. hamers et al.