A novel adjuvant, mixture of alum and the beta-adrenergic receptor antagonist propranolol, elicits both humoral and cellular immune responses for heat-killed Salmonella typhimurium vaccine

To determine the efficacy of the mixture of propranolol (PRP), a beta-adrenergic receptor antagonist,
and alum, as a new adjuvant, in the induction of humoral and cellular immunity in response to
heat-killed Salmonella typhimurium (S. typhimurium) (HKST) as a model vaccine.
Methods: BALB/c mice were divided into five groups. Mice in the experimental groups received either the
HKST vaccine alone or in combination with the adjuvant alum, PRP or the alum–PRP mixture. Mice in the
negative control group received phosphate-buffered saline. All mice were immunized two times on days
0 and 14. Two weeks after the last immunization, immune responses to S. typhimurium were assessed.
Results: Administration of the alum–PRP mixture as an adjuvant increased the ability of the HKST vaccine
to enhance lymphocyte proliferation, shifted the immune response towards a T-helper (Th) 1 pattern and
increased S. typhimurium specific IgG, IgG2a and IgG1. This resulted in improved protective immunity
against S. typhimurium.
Conclusion: Administration of the alum–PRP mixture as an adjuvant in combination with the HKST vaccine,
can enhance both humoral and cellular immunity and shift the immune responses to a Th1 pattern.