Typically, the killed form of microorganisms in combination with alum does not produce strong cellular immune responses. A recent investigation has indicated the role of dopamine D2 receptor antagonists like metoclopramide in reducing the polarization of immune responses toward Th2 immunity. This study was performed to evaluate the effects of a combination of alum and metoclopramide on the induction of cellular and humoral immunity in response to a heat-killed preparation ofSalmonella typhimurium(HKST). Wistar rats were immunized with the HKST vaccine alone or in combination with alum, metoclopramide, or the alum-metoclopramide mixture twice with a two-week interval. Fourteen days after the last vaccination, immune responses against S. typhimurium and the protective potential of the vaccines were assessed. The combination of alum and metoclopramide as an adjuvant augmented the potential of the HKST vaccine to enhance lymphocyte proliferation, delayed-type hypersensitivity reaction, and antibody titer. These results were concurrent with the polarization of immune response towards the Th1 response and improving protective immunity against S. typhimurium. Overall, the combination of alum and metoclopramide as an adjuvant synergistically enhanced cellular and humoral immunity after immunization with the HKST vaccine.
Keywords: Adjuvant; Alum; Metoclopramide; Salmonella typhimurium; Vaccine.
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