Adjuvants and immune system
Hi guys, here me again Jonathan Makassa. As you probably know I’m obsessed about biotechnology. Today I want to talk about adjuvants. If you’ve watched our previous than you will know that adjuvants are a component that is often used in vaccines. Especially in nucleic acid vaccine to increase their effectiveness and there is actually no need to be afraid of them.
Before we dive into that let’s talk about the immune system. Every day in our usual activities we come in contact with some pathogens. They are bacteria and viruses that can cause illnesses. But luckily for us our body has a natural defense system that we call the immune system.
How does it work? Immune system can be split into two parts: the innate defense system and adaptive defense system. The innate defense system begins with external membranes such as skin and different mucuses that separate what is inside from what is outside. But sometimes if pathogen can pass through the barrier and enter inside the organism, we have internal defenses such as phagocytes and anti-microbial proteins lysosomes and other entities that can find the intruders and kill them. We also have killer cells, natural killer cells, that could find those - sometimes it could be cancer cells or viruses or bacteria – to target them and kill them.
Then comes the adaptive defense system. This system is a bit more sophisticated because it creates a specific response to a specific type of antigen. This is made possible because of proteins called antibodies. Antibodies are particular proteins that are able to target recognize antigens, tag them and call the cells that come to kill them. It could be phagocytes or natural killer cells. But sometimes these antibodies have limits. That is when the vaccine steps in and as I said before some vaccines use adjuvants to increase their efficiency. In brief adjuvants are chemical substances that increase the effectiveness of vaccines. Especially those have a low immunogenicity.
How do they do that? Well, there are several mechanisms of adjuvants. The first one is precipitation. One of them is the aluminum potassium sulfate, or alum. The alum precipitates the antigens and doing so it increases its size and makes it possible the contact between the antigens and the phagocytes. Besides that by precipitating the antigens these adjuvants create inflammation in the size of injection so that the macrophages and all B and T-cells are alarmed and they could come and to the size of injection to kill the antigens. Doing so it increases the immune response increases.
Apart from precipitation there is another mechanism. Here we have the famous Freund’s incomplete and complete adjuvants (IFA and CFA). IFA contains antigens in an aqueous solution mineral oil and emulsifying agent. The complete freund’s adjuvants (CFA) contain that but in addition to all these elements they have macrobacteria that can release a substance called muramyl dipeptide. This molecule can activate macrophages and we all know that activated macrophages contain a high level of MHC class 2 and b7 that can enhance the immune response. It is the way how adjuvant can increase the immune response of vaccines that have a low immunogenicity.