Adjuvant immune response

Adjuvants are substances which can modify the immune response of an antigen (139,140). With better understanding of the functions of different arms of the immune system, it is possible to explore the effects of an adjuvant, such that the protective efficacy of a vaccine can be improved. At present, aluminum salt is the only adjuvant approved for use in human vaccines. New adjuvants such as QS-21, 3D-MPL, MF-59, and other liposome preparations are being evaluated. Several of these adjuvants have been in clinical trial, but none have been approved for human use. IL-12 has been proposed as an adjuvant which can specifically promote T-helper 1 ceU response, and can be a very promising adjuvant for future vaccine development. 

Biodegradable Nanoparticles as Vaccine Adjuvants and Delivery Systems Regulation of Immune Responses by Nanoparticle-Based Vaccine... 

Vaccination to induce an adaptive immune response is expected for a broad range of infectious diseases and cancers. Traditional vaccines are mainly composed of live attenuated viruses, whole inactivated pathogens, or inactivated bacterial toxins. In general, these approaches have been successful for developing vaccines that can induce an immune response based on antigen-specific antibody and cytotoxic T lymphocyte (CTL) responses, which kill host cells infected with intracellular organisms (Fig. 1) [1,2], One of the most important current issues in vaccinology is the need for new adjuvants (immunostimulants) and delivery systems. Many of the vaccines currently in development are based on purified subunits, recombinant... 

Raghuvanshi RS, Katare YK, Lalwani K et al (2002) Improved immune response from biodegradable polymer particles entrapping tetanus toxoid by use of different immunization protocol and adjuvants. Int J Pharm 245 109-121... 

A corollary to the use of cBSA as a carrier protein is that its increased immune response often abrogates the use of complete Freund s adjuvant, which is a source of concern because of its potential side-effects in animals. A relatively innocuous mixture with alum is usually all that is required as adjuvant to result in good antibody production. 

Polyclonal antibody preparations have been used to induce passive immunity against a range of foreign (harmful) agents, and vaccines are used efficiently, and safely, to promote active immunization. Adjuvants are usually co-administered with the vaccine preparation, in order to enhance the immune response against the vaccine. 

Despite their popularity, aluminium-based adjuvants suffer from several drawbacks. They tend to stimulate only the humoral arm of the immune response effectively. They cannot be frozen or lyophylized, as either process promotes destruction of their gel-based structure. In addition,... 

A variety of lipid adjuvants and protein mediators have also been shown to influence the immune response to antigens encapsulated in liposomes. The most widely used examples of such adjuvants for practical immunization procedures are endotoxin (including lipid A and lipopolysaccharide) and numerous types of lipophilic derivatives of muramyl dipeptide. 

The effect of alum as adjuvant was also tested in the liposphere-vaccine formulation. In the presence of lipid A, enhanced immune response is obtained even in the absence of alum. This observation is very important because there is increasing concern about the toxic side effects of alum in the long term. Research has suggested a link between aluminum and diseases of the brain, including Alzheimer s disease. 

The adjuvant effect of lipid A on the immunogenicity of polymeric lipospheres was also tested [14], Incorporation of lipid A in PCL lipospheres had no effect on the IgG ELISA titers. However, in the case of PLA lipospheres, lipid A significantly increased the immune response to R32NS1 malaria antigen, resulting in IgG levels similar to those obtained with PCL lipospheres. The adjuvant effect of lipid A incorporated in PLA lipospheres was observed even after 1600-fold dilution of the rabbit sera [14],... 

It is reasonable to presume that the immunogenic and adjuvant activity of lipospheres may be the result of a combination of factors. These factors may include a focused and enhanced delivery of the antigen to an antigen-presenting cell (macrophage) and protection of the antigen from metabolic destruction at other sites in the body that do no participate in the immune response. 

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