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Lecture 12 - Autoimmune Hemolytic Anemia

Lecture 12 - Autoimmune Hemolytic Anemia - Lecture 12...

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Lecture 12 – Autoimmune Hemolytic Anemia - - Plasma derived medeators in inflammation: three interrelated systems: complement, kinin, clotting systems Complement products (C5a, C3a, C4a) Plasma (produced in liver) Leukocyte chemotaxis and activation, vasodilation (mast cell stimulation) Kinins Plasma (produced in liver) Increased vascular permeability, smooth muscle contraction, vasodilation, pain Proteases activated during coagulation Plasma (produced in liver) Endothelial activation, leukocyte recruitment Complement - Produced mainly in the liver o In the circulation as inactive precursors o Activated by a series of proteolytic cleavages o C1-C9 - Activated by bugs and the dead o Microbial products, necrotic cells, and the proteins of the complement, kinin, and coagulation systems, which are themselves activated by microbes and damaged tissues. - Once activated/released, quickly de-activated/scavanged o Body will keep the complements in check - Cause increased o vascular permeability (vasodilation), o chemotaxis (recruitment of WBC into target site), o opsonization (phagocytosis of bacteria by macrophages) - The main players are the activator ( a at the end) o C5a, C3a - The complement can be activate by three different pathways 1) Alternative pathway 2) Classical pathway 3) Lectin pathway - Class pathway -- related to antibody production o Basic structure of an antibody look like a Y (hyper-variable region of the Ig at the V tips, and the long end has the constant portion that does not change a lot) o This is the classical pathway how the complement activated by c1 and bacteria itself can be activated C5b - Bottom line is that they turn on the activator C3 and cleave off the C3a and the C3b will be stuck on the micro itself - C3a can be attached to neutrophil and further activate C5a and 3a and activate the microbes destroyed by leukocytes - The microbe with C3b can cause phagocytosis -- takes in the microbe into cytoplasm - C5b gets activated through that and it activates MAC (membrane attack complex— activated C6-C9) o Forms a hole in the organism and causes the lysis of them microbe organism - The main functions 1) C5a, C3a – INFLAMMATION 2) C3b – phagocytosis 3) MAC lysis o Inflammation- C3a, C5a (C4a)-increase vascular permeability and cause vasodilation- anaphylatoxins Vasodilation so that chemical can be pushed in and out C5a-chemotaxis and activates lipoxygenase pathway causing release of inflammatory mediators o Phagocytosi s- C3b acts as opsonins and promote phagocytosis by neutrophils and macrophages Happens every quickly once complement is activated o Cell Lysis Deposit of MAC on cells-cells permeable to water and ion cause lysis (death) of the cells Complement System (More on it) - Activation is tightly regulated - Normal cells express regulatory proteins to prevent cell injury by complement activation - Regulatory proteins inhibit activated complements or remove fragments deposited on cells - Can overwhelm regulatory proteins on normal cells by large deposit of complements (i.e. autoimmune disease, sepsis, hemolytic anemia)
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