The classical pathway of complement

Published on December 31, 2017   50 min
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Ladies gentlemen, my name is Mohamed Daha. I'm professor emeritus at Leiden University Medical Centre, and my email address is written below, and so in case you'd like to contact me, please feel free to do so. So in order to understand what the position of complement is in our innate immune system and acquired defense, I would like to give you a view what innate and acquired immunity is.
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Innate immunity is the immunity by which your born except the antibodies that you have received from your mother via the placenta before or during birth. Innate immunity is composed of a number of cells. The first place NK cells, Macrophages, Dendritic cells also known as antigen presenting cells and Granulocytes or PMNs. Next to these cellular components, there are a number of soluble mediators called Cytokines, Chemokines, Defensins and Pentraxins. And the main pillar in this soluble mediators is the complement system. Complement is very important for the recognition of antigens. This can directly be recognized by dendritic cells. For instance, complement facilitates the recognition and leads to a much better presentation of antigens to, for instance, T lymphocytes and B lymphocytes. T lymphocytes and B lymphocytes are recognized the processed antigens and then result in activated T cells and B cells leading to production of antibodies. Next to production of antibodies and activated T cells, there are a number of soluble products that you see, Cytokines and chemokines which also directly affect and feed back to innate immunity. So as you see complement is very important in the sense that if, for instance, if you are deficient in the complement system, you are not really able to mount a sufficient and effective acquired immunity. And many investigators have shown that deficiencies of complements are very important for the mounting of an efficient immune response and especially the production of antibodies.