Medical Fact of the Day – How You Make Antibodies
Over your lifetime you will encounter countless types of pathogens, including bacteria, viruses, and parasites. Additionally, aberrant cells within your body like tumor cells need to be recognized to be killed. Your immune system recognizes all these potential dangers by creating receptors for them - that is, proteins that have a specific shape to recognize other proteins and molecules.
Yet for each type of pathogen, there are countless variants that you might encounter. Over 200 types of viruses can cause the common cold, each expressing different types of proteins that need to be recognized. Furthermore, each individual cell only recognizes one specific shape. How is your immune system able to recognize so many different things?
The answer is an elegant solution to generate diversity called VDJ recombination. Each antibody you make consists of multiple gene segments that are combined together from a much bigger pool. The process is like shuffling three decks of cards and choosing a single card from each deck to create a unique combination for each cell.
One gene from each collection is chosen to form the final product.
For instance, part of the antibody is called the heavy chain. This region contains 65 Variable (V) genes, 27 Diversity (D) genes, and 6 Joining (J) genes. This means there are 65 x 27 x 6 = 10530 combinations. Furthermore, there can be minor modifications in the sequences between genes. Overall, this means that your immune system can recognize billions of different shapes from just a limited set of genes.
The human body really is amazing.
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