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Immunology - Antibodies (Immunoglobulins) (*DIRTY USMLE antibodies…

- - - - Compliment and Phagocytic Attachment Sites
        
        FAGS don't Fc their compliment
        
        Compliment binding site on Immunoglobulins
        
        Notes:
        
        the Ci compliment binds to the Fc portion of the antibody on ONLY IgM and IgG
        --> recall these are the only 2 antibodies that can activate the compliment system
        
        example:
      - Gamma Immunoglubulins
        
        note that globulins in general as a protein class can be grouped by their molecular weight by gel electro
        
        GAM of immunoglobulins are gamma globulins
      - Heavy Chain
        
        defines the 5 subtypes of antibodies
        
        coded for by different exons and mRNA splicing
    - - *IgG
        
        IgG is the major opsonin
        --> helps phagocytes eat bacteria
        
        Notes:
        
        both IgM and IgG are first responders to any pathogen and good activators of the complement system
        --> IgM since it is the first antibody present on B cells before class switching
        --> IgG since it is the most abundant antibody in the serum
        
        IgM valence = 2
        
        IgG only antibody that can cross the placenta barrier
        --> IgG gives neonates immunity for first 6 months of life
        
        *IgM
        
        IgM "makes" all other antibodies
        
        Notes:
        
        both IgM and IgG are first responders to any pathogen
        --> IgM since it is the first antibody present on B cells before class switching
        --> IgG since it is the most abundant antibody in the serum
        
        IgM as B Cell receptor
        --> valence = 2
        
        IgM as in serum = pentamer
        --> valence = 10
        
        *IgD
        
        IgD tells B cells they are "DONE" maturing in bone marrow
        
        Notes:
        
        IgD valence = 2
        
        very low serum count
        
        IgD exist with IgM on the Bcells as B cell receptors when they are in the bone marrow
        
        IgD cells tell the B cells they are "DONE" maturing and to leave the bone marrow
        
        think of IgD = B cell driver's liscence
        --> once they express IgD they can leave the bone marrow and DRIVE around the body's lymphatic system
        --> they are amture at this point, but NAIVE
        
        *IgA
        
        IgA "Airways and mucosA surface Area"
        
        IgA dimer transport through enterocytes to GI lumen mucosa
        
        Notes:
        
        IgA valence = 2
        
        in serum forms dimers --> valence = 4
        
        since IgA is important for surface Area mucosa and airway immunity against infection
        
        babies have IgG from mother for first 6 months through placenta transport
        
        but babies need respiratory protection
        --> they get IgA from mother's breast milk
        --> protection fro RTIs
        
        IgA deficiency
        
        body either doesn't produce IgA or build IgE antibodies against your own IgA
        
        Notes:
        
        note that IgA deficient patients can react to blood transfusions since there is a possibility IgA to be in blood
        
        IgA migration through enterocytes to gut lumen
        
        IgA GI enterocyte transport requires 2 things
        --> J CHAIN and SECRETORY component
        
        J CHAIN = needed to form the IgA dimer
        
        SECRETORY component = needed in the cytosol and lumen to stop our body from breaking it down
        
        *IgE
        
        IgE = "Elergic reactions"
        
        Notes:
        
        IgE valence = 2
        
        in serum very low amount, mostly are attached firmly to granulocytes by Fc receptors
        
        granulocytes
        --> mast cells
        --> basophils
        --> eosinophils
        
        IgE good for complex pathogens like parasites and worms
        
        also for ELlergic reactions
        
        2 Functions of IgE
        
        Ellergic Reactions
        --> antibody mediated degranulation
        
        Parasitic cell-mediated cytotoxicity
        
        IgE Parasitic cell-mediated cytotoxicity example
        
        Case presentation:
        
        Notes:
        
        note that