What is an adjuvant, with examples of immunological applications

Adjuvant is a non-specific immunostimulant that is injected into the body at the same time as the antigen to enhance the immunogenicity of the antigen or the immune response of the body. On the one hand, adjuvants can change the physical properties of antigens, delay the degradation of antigens, and stimulate the antigen-presenting cells to enhance their processing and presentation of antigens, and on the other hand, they can stimulate the proliferation and differentiation of lymphocytes to enhance and expand the immune response. Adjuvants can be divided into biological adjuvants, such as BCG, inorganic compounds aluminum hydroxide, organic mineral oil; liposomes, such as immune-stimulating complexes. Different types of adjuvants have different effects and mechanisms.