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The complement system in innate and adaptive immunity: normal functioning of the complement system

Part 1 of 2
Published on November 30, 2021   44 min

Other Talks in the Series: The Immune System - key concepts and questions

0:00
Hello, my name is Steven Sacks, I'm an academic nephrologist, which means I specialise in kidney disease and see patients, and I also do research. My research topic is the complement system, concerning my particular field in transplantation and kidney disease. I'm going to talk today about the complement system, and the relationship to the innate immune response and the adaptive immune system.
0:30
Let me pause for a minute just explain one or two points, which will carry through the talk. The first is that the complement system was discovered in the blood. Some remarkable scientists, about 120 or 130 years ago, recognised that serum had within it two key components. The first was a heat-labile component and the second a heat-stable component, and both of those components could, together, collaborate to kill microorganisms. The heat-stable component later became known as antibodies, and the heat-labile (heat-sensitive) component became known as the complement system. There you have in a nutshell - described that long ago (120/130 years ago) - outlined, the title of the talk: how the innate and adaptive arms of the immune system interact, to defend against infectious pathogens. There have been changes since then, first of all the concept of the adaptive system has widened to include T-cells, as well as B-cells which produce antibodies, that's the first point. Point number two is that the complement system is needed, not only to effect a response of antibodies and T-cells, but also to prime that response. The effect of complement is involved in both priming and mediating the effects of the adaptive immune system. Even though the complement system is more ancient, by many millions of years, than the adaptive immune system, the two have integrated, and in mammals are both important for an immune response. A further point - and this is important - is that although complement was first described in the blood, most cells in the body (in most tissues and solid organs) produce their own complement components. It's not absolutely clear why, but the evidence points to distinct functions, we'll come across this later. Complement is a compartmentalised system, and that level of understanding is important in designing how to measure complement, how to use it as a marker, and how to target it therapeutically. Let me outline the talk and how I want to divide it, I've split it into two parts.
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The complement system in innate and adaptive immunity: normal functioning of the complement system

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