How Vaccines Work: Adjuvants

Many people throughout the public and even some in the scientific community have a misconception about vaccines due to a lack of understanding. Most people do know understand the science behind vaccines and what vaccines actually do and how they do it. The main mechanism that occurs in a vaccine is through the use of adjuvants. Most people have never even heard of the word adjuvant among the general public and some scientist as well. In this post I will describe you what exactly an adjuvant is how it works to allow you to have a better understanding of vaccines.

An Adjuvant is something that is added to vaccines that will enhance the body’s immune response to a certain virus or bacterial infection. The Adjuvant produces a stronger immune response for the adaptive immune system and allows the body to produce more memory cells for that particular virus then if the adjuvant had not been apart of the vaccine. A vaccine usually consists of a small amount of the dead virus or bacteria or just protein components of the certain virus along with the adjuvant. The use of adjuvants in vaccines dates back to the 1930’s where aluminum was the most common. In todays vaccines the most common adjuvant used is Aluminum Hydroxide Gel commonly called Alum. Alum increases the attraction and uptake of the invading antigen by antigen presenting cells (APC’s) allowing them to present more antigens to B and T-cells. By using adjuvants you all greatly increase the odds that the vaccination will in fact work and it will increase the longevity of the vaccine, increasing the adaptive immunity time for that certain antigen.

In order for the vaccine to be successful the use of adjuvants is critical, the adjuvant plays a vital role in the enhancement and directing of the adaptive immune response to the specific vaccine antigen. The immune system is composed of two components, the innate immune system and the adaptive immune response. The adaptive immune response is responsible for immunological memory and being able to react to a specific virus or bacteria through past memory. The adjuvant enhances the ability of the adaptive immune system to have a stronger response to a certain disease through immunological memory. The adjuvant is what enhances this response and allows the body to recognize the antigen and provide and much more rapid and strong response when exposed. This allows the body to kill the antigen before it has a chance to spread and take hold in the body. By enhancing the immune response of the adaptive immune system you are also strengthening the innate immune system through antigen presenting cells binding to more antigens and having a faster response to the antigen.

All adjuvants function to provide immunological memory to a certain virus or bacteria and also to enhance that specific response if exposed. The way that an adjuvant accomplishes this may vary between different adjuvants. The most common adjuvant alum has a distinct mechanism from the rest. Alum works as a sort of delivery system of the antigen to the body, it functions by creating a large deposit of antigens where the virus is injected. The function of the depots is to the trap the antigens at the site of infection allowing the slow release of the antigens to the immune system. This creates a slow and steady release of the antigen and allows the immune system to be stimulated for a much longer period of time. By doing this the immune system is exposed to the antigen for a much longer time causing the increased recruitment and activation of the antigen presenting cells of the immune system. The adjuvant alum is also able to bind to multiple antigens and forming a larger collection of multiple antigens, which are easier for the antigen presenting cells to uptake and increases the amount of antigens bound to the antigen presenting cells. By doing this you increase the exposure time of the antigen to the immune system and enhance the ability of the immune system to recognize and bind to the antigen.

From the use of adjuvants in vaccines we are able to use a non-active form of a virus or bacteria in small dose and provide them with immunity to that specific antigen. Because of adjuvants we are also able to enhance the strength of the adaptive immune response and are able to greatly increase the time that the adaptive immune system will remember this specific antigen. So instead of getting a vaccination for a particular antigen every five years you now only have to get the vaccination every ten. I hope that this information about how vaccines actually work provides you with some clarity about what exactly vaccines do. Knowing this now you can hopefully eliminate whatever concerns or doubt that you had regarding vaccination.

 

References:

http://www.invivogen.com/review-vaccine-adjuvants

http://www.cdc.gov/vaccinesafety/concerns/adjuvants.html