Category Archives: Daily Q&A

Q&A: What is an adjuvant in vaccine? Its relationship to danger theory.

An adjuvant is one of the ingredients widely incorporated into vaccine. One of the examples is aluminum hydroxide. Aluminum-containing chemicals, known as alum, are often referred to as adjuvant added to the vaccine. The function of adjuvant is to boost up the immune response to the antigen inside the vaccine. Without adjuvant, antigen has to arrive at the lymph node to activate the immune system. With adjuvant, antigen can be detected much early on, and be migrated along with antigen presenting cell to the lymph node.

The exact mechanism of how adjuvant works is yet known. All we know is that adding adjuvant recruits immune cells near the site of injection. It is been proposed that adjuvant damages tissues. The damaged tissue releases uric acid which signals for the presence of “danger” or foreign pathogens inside the host. As a result, the host is more responsive to the antigens inside the vaccine.

Q&A: How are monoclonal and polyclonal antibodies made?

The production of both antibodies starts off the same. Scientists inject the antigen along with an adjuvant (to stimulate immune response) into an naïve animal. The animal generates an immune response, and B-cells start to proliferate and generate a repertoire of antibodies that can target the antigen.

What is the difference between monoclonal and polyclonal antibodies?

Each B-cell generates a different antibody that looks for different thing (epitope) on the antigen.

To make the polyclonal antibodies, you simply extract the serum from the blood of the animal. The serum, also known as antiserum, contains the polyclonal antibodies which can target multiple targets. The varying target ability of polyclonal antibodies is due to its collection of antibodies coming from multiple B-cells. However, this raises concern regarding the batch-to-batch variation because of affinity maturation and class switch recombination.

How to dilute antibodies?

To make monoclonal antibodies, after injection, you collect the B-cells that present different antibodies on the surface. Then, fuse B-cell with immortalized B-cell because B-cell normally has a relatively short lifetime. After fusion, you create a hybridoma. Then you need to select which hybridoma is the best to detect your antigen, by testing with western blotting or dilution approach. After that, you select the best hybridoma and that’s the immortalized cell line that can give you a continuous amount of monoclonal antibodies.

Q&A: What is the difference between monoclonal and polyclonal antibodies?

Monoclonal antibodies are derived from a single immortal B-cell line. Thus, monoclonal antibodies can only recognize one single epitope on your antigen.

How to dilute antibodies?

In contrast, polyclonal antibodies are derived from the serum collected from animals exposed to the antigen. Thus, polyclonal antibodies are in fact a collection of antibodies generated from many B cells.

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