Mechanisms of Acquired Immunity

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Mechanisms of Acquired Immunity


Lecture number:
31
Pages:
6
Type:
Lecture Note
School:
University of Southern California
Course:
Bisc 307l - General Physiology
Edition:
1
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BISC 307L 1st Edition Lecture 31 Current Lecture  Immunoglobulins o o If you take serum proteins they are pretty much all globular proteins so called globulins (5 classes)  1st class: A- albumin (not called a protein though)  A1, A2, B, Gamma are the other four which are classified by molecular weight ( gamma ones are antibodies- also known as immunoglobulins (Ig))  There are 5 classes of Ig. All secretions of activated B lymphocytes  1. Most abundant in plasma is IgG  4 parts (2 identical light chains and 2 identical heavy chains  y shape  constant C and variable V regions  Fab= when you digest Ig with enzyme called papain it is cleaved into antigen binding fragment  Fc= The other part it is cleaved into is crystallizable fragment  2. IgD- structure has a pink transmembrane region. B cell receptor.  3. IgM- first Ig secreted by B cells.  Large molecule  Cannot leak out of capillaries (even inflamed ones)  Action is in the blood  After a month of secreting this it undergoes class switching (the constant region is switched from IgM  IgG) not in the antigen binding region  The IgG has the same identical antigen binding specificity as IgM which will have the same specificity as IgD: therefore this cell will only make antibodies that have this particular specificity  4. IgG  smaller molecule and leaks out during inflammation  only maternal antibody that can cross the placenta  helps confer passively some of the mothers immunity onto the fetus  some plasma cells when they switch from IgMIgG they may switch to IgE instead. This is abnormal: TRIGGERS ALLERGIES  5. IgE  allergies  abnormality  parasitic worm infections  6. IgA  most abundant form for mucus secretions (milk tears, mucus)  Transcytosis of IgA



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