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Clinical immunology 321 - Coggle Diagram

- - - - a collection of circulating and membrane associated proteins. Many are enzymes and are involved in activation cascades.
      - most complement proteins made in liver
      - alternative pathway is triggered when some complement proteins are activated on microbe surfaces
      - Classical pathway activated when antibodies bind to microbes or other antigens.
      - Lectin pathway activated when a plasma protein, mannose-binding lectin, binds to terminal mannose on the surface glycoproteins of microbes.
      - central component is plasma protein C3 which is split up into major fraction, C3B and becomes covalently attached to microbes and activates downstream complement proteins on microbe surface.
      - 1) C3b coats microbes and promotes binding of microbes to phagocytes
        2) breakdown products of complement proteins are chemoattractants for neutrophils and monocytes and promote inflammation at site of complement activation.
        3) complement activation culminates in the formation of a polymeric protein complex that inserts into membrane, disrupting permeability barrier and causing osmotic lysis or apoptotic death of microbe.
- - - - B lymphocytes differentiate in bone marrow. Thymus is specifically for T cell maturation.
        
        Both B and T cells encounter antigens in secondary lymphoid organs, for example lymph nodes.
- - - - Stem cells in bone marrow contain Ig and TCR genes
        
        The heavy chain and light chain and the TCR A and B chains each contain V regions and C regions.
        
        Between the V and C regions, there are J and D regions
        
        The commitment of a B lymphocyte to become a B lymphocyte is associated with recombination of one Ig heavy V gene segment with a D and J segment, leaving a recombined VDJ gene in the heavy chain locus.
      - 1) a process cataylsed by RAG1 and RAG2.
        2) Cleavage of hairpin structures in DNA and joining of the DNA ends.
        3) hairpin may be asymmetric and this is filled in with extra P nucleotides.
        4) In heavy chain genes, extra N nucleotides can be added
        5) exonuclease nibbling can also modify the number of N and P nucleotides in the final genes.
      - In theory, B cells could display more than one light and heavy chain but this often leads to autoimmunity and autoantibodies, so a process called allelic exclusion does this.
        
        two seperate chromosomes for heavy and light chain/
        
        more focused on light chains because they are involved in antigen binding.
        
        kappa and landa light chains.