Induction of type 1 cytokines during neem leaf glycoprotein assisted carcinoembryonic antigen vaccination is associated with nitric oxide production

Involvement of the nitric oxide (NO) release in CEAMϕNLGP (carcinoembryonic antigen pulsed macrophages with neem leaf glycoprotein) vaccination and its relationship with vaccine induced type 1 immune response were aimed to study in the present communication. Vaccination with CEAMϕNLGP resulted in macrophage activation as evidenced by its increased number and expression of CD69 marker. Activated macrophages demonstrated upregulation in synthesis of IL-12 and downregulation in IL-10, along with excess IFNγ production in splenic cells, as evidenced from mRNA analysis. Induction of such type1 immunity was further confirmed by expression of type 1 specific transcription factor, T-bet and enhancement of intracellular glutathione content. Such vaccination also induced greater nitric oxide (NO) production from macrophages. Dependence of induced type 1 immune response on the NO release and vice versa was studied by in vitro neutralization of IFNγ/IL-12 and in vivo inhibition of NO production by methylene blue. Obtained results clearly demonstrated the interdependence of two anti-tumor immune functions, namely, NO production and generation of type 1 immune response. Understanding of the mechanism of this NO related immune modulation would have great impact in proposing CEAMϕNLGP vaccine in clinic for the treatment of CEA+ tumors.