Propranolol efficacy as a novel adjuvant for immunization against Toxoplasma gondii tachyzoites

Severe or lethal damages, caused by Toxoplasma gondii infection in congenital cases and immunocompromised
patients implies the necessity for development of a vaccine and an appropriate adjuvant would be needed to
elicit a protective Th1 biased-immune response. The adjuvant activity of propranolol was surveyed and compared with alum by immunization of BALB/c mice with protein components of T. gondii tachyzoites. Five groups
of BALB/c mice were immunized with phosphate buffered saline (negative control), Toxoplasma lysate antigen
(TLA), alum plus TLA, Propranolol plus TLA, and alum, propranolol and TLA. Immunization efficacy was
evaluated by lymphocyte proliferation and DTH tests, challenge with live tachyzoites, IFN-γ production by
spleen cells, serum TNF-α concentration and anti- Toxoplasma total IgG, IgG1 and IgG2a measurements. Mice of
the PRP-TLA group induced significantly more IFN-γ and TNF-α production and lymphocyte proliferation than
other groups. This group of mice also showed more anti-T. gondii IgG2a and DTH responses and showed a
significantly increased survival time after challenge. These findings indicate that propranolol as an adjuvant in
combination with TLA, may enhance cellular immunity against T. gondii