Immunology Lecture 2. Flashcards
What is antibody?
activity/clumping against antigen
Which immunoglobulin is most common in the blood?
IgG
Which immunoglobulin is first one made in an immune response?
IgM
Which is the largest immunoglobulin by mass?
IgM
Which immunoglobulin has the longest half life?
IgG (most stable)
Which immunoglobulin has the shortest half-life/lowest serum level and why?
IgE - sticks to cells very quickly - does not need bound antigen to bind to cells
Which immunoglobulin activates the complement system?
IgM (most potent)
Which immunoglobulin can transport across the placenta?
IgG (baby has mother’s profile of IgGs)
Which immunoglobulin can transport across epithelium?
IgA (as a dimer) - in secretions
How do IgG and IgE differ?
IgG needs bound antigen to bind to cells, IgE does not (very sticky)
What are the main functions of IgG?
toxin neutralizing (tetanus!), agglutinating, opsonizing, bacteriolytic
Why does IgM require complement for opsonization?
immune cells do not have IgM
What is the secretory piece of IgA?
T-piece - resists acid hydrolysis
What form is IgM predominately found?
pentamer - held together by J chain and disulfide bonds
What form is IgA predominately found?
dimer - has j chain between - highly glycosylated
What is the function of IgD?
co-expressed with IgM on surface of B-lymphocytes, associated with some tumor cells
What is the function of IgE?
Immediate hypersensitivity (allergies) - fixes to mast cells BEFORE antigen is bound - cross linking causes release of histamine from mast cell - used to be used to clear parasites
What is the structure of IgE
similar to IgM
What did we find by proteolytically degrading immunoglobulins?
constant region is crystallizable and binds to Fc receptor, variable region can’t crystalize, binds only antigen
What are hypervariable regions?
provide the sequence of the very specific antigen binding site
How many hypervariable regions per antibody?
three - spread out linearly, but close together in space
