In this investigation, we evaluated the immunomodulatory
activities of an ethanolic extract of A. paniculata
(APE) and andrographolide (AND), one of the bioactive
principles, administered by the oral route in mice
immunised with an inactivated Salmonella typhimurium
vaccine, the latter having been previously reported to
induce only humoral (antibody) response but little or no
cell-mediated immune response or immunity (CMI) in
the mouse model [15–17], although in chickens, a killed
Salmonella enteritidis vaccine was reported to induce
splenocyte lymphocyte proliferation following stimulation
with Con A, a T-cell mitogen, in an apparent agedependent
manner [23]. We opted for the mouse model
for this investigation because of the demonstrated
inability of the killed Salmonella vaccines to induce
CMI in this model.
Our results demonstrated that both the Andrographis
extract and andrographolide enhanced not only
Salmonella-specific serum IgG antibody levels in
vaccinated mice but also induced CMI as judged by
production of a CMI-indicator cytokine, INF-γ, in the
Salmonella lysate-stimulated splenocyte supernatants.