Antibody Function and Complement Flashcards
What makes IgA Antibodies?
Plasma Cells in lymphoid tissues
What is the Secretory Component?
The receptor bound, exocytosed IgA. This is our first line of immunological defense in the gut against invading organisms.
Where else is IgA found?
Some monomer and dimer found in the plasma.
What is the importance of IgD?
It is a B cell receptor. We will learn about it more later.
IgE binds to what?
corresponding receptors on mast cells and basophils.
When IgE binds to _____ it induces the release of what?
basophils and mast cells. It triggers the release of histamine and in the case of mast cells only it triggers the release of eosinophil chemotactic factor. Eosinophils are important in killing parasites.
What are the three ways to activate the C cascade? All three pathways attempt to activate what?
- classical
- alternative
- Lectin
C3
The classical pathway deals with what antibodies?
IgM and IgG
Why is IgM a more efficient activator than IgG?
C1q must be bound by two Fcs simultaneously. It must either bind two IgGs at the same time that are close to each other or one IgM. Either one must be bound to an antigen to fit in the C1q.
what is the Classical C count in the pathway?
142356789
What inhibits Complement activity?
C1-inh (or C1 esterase inhibitor)
what is typical of the a and b components of a C molecule (e.g. C3a and C3b)?
b (Bound) usually stays bound to the membrane while a (away) usually floats away for further biologic activity.
how is the alternative pathway activated?
certain cell wall structures of microorganisms (e.g. a bacterium can activate Complement this way without an antibody. It is part of the innate immune system.
How does the alternative pathway work?
The cell wall provides a surface for the binding of properdin (P) which anchors C3b, factor B, and factor D. A trimer is formed: C3bDbC3b which can activate C5 and continue the cascade.
What activates the Lectin Pathway (specifically)?
A Lectin called Mannose Binding Protein (MBP or MBL).
