Term
| What type of chains do antibodies have? |
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Definition
2 heavy chains
2 light chains |
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Term
| What genes make light chains? |
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Definition
| kappa and lamba... and both of the light chains will be made by the same gene on a single antibody |
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Term
| Antibody function is defined by its _ region |
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Definition
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Term
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Definition
| the constant region where the effector function is |
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Term
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Definition
| The variable part of the antibody that has the antigen-binding sites |
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Term
| Name the different classes of antibody |
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Definition
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Term
| What antibody classes are monomers (3)? |
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Definition
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Term
| What antibody class is a dimer? |
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Definition
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Term
| What antibody class is a pentamer? |
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Definition
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Term
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Definition
| The J chain is on the IgM pentamer, and it is the part that binds, leaving the tips out like spider legs! |
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Term
| True or false: antibodies don't kill |
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Definition
| true! They don't kill, they help other things kill |
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Term
| Name the 4 functions of antibody |
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Definition
1. Opsonization for phagocytosis
2. Fix complement
3. Block attachment
4. Neutralizes toxins |
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Term
| Explain opsonization for phagocytosis. |
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Definition
When bacteria have antibody on their surface, they are "candy-coated"and 1000 time more likely to be phagocytosed.
- Macrophages and neutrophils have Fc receptors on their surface, so when bacteria have antibody (and therefore Fc regions) on them they are more yummy and more likely to be phagocytosed because the Fc region of the antibody binds to the Fc receptors on the macrophage or neutrophil |
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Term
| Explain fixing complement |
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Definition
Antibodies bind to bacterial cell surface antigens 40 nm apart.
A C1 complement complex had many arms that need to bind to antibodies. The arms are 40nm apart.
When it binds, this initiates a complement cascade which activates a MAC attack |
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Term
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Definition
Membrane attack complex
- a complex that forms on the surface of bacterial cells and forms transmembrane channels that disrupt the phospholipid bilayer of the target cell, so it can't maintain osmotic pressure.
This leads to cell death. |
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Term
| Which complement proteins are involved in the MAC attack? |
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Definition
| C5-9 form tubes which poke holes or channels in the bacterial cells |
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Term
| Explain how antibody blocks attachment. |
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Definition
Without antibody, surface proteins on viruses would freely bind to receptors on the target cell.
Antibody binds to surface proteins on viruses and blocks the virus from biding to receptors on the target cell. This also works for some bacteria and extracellular protozoa |
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Term
| Explain neutralization of toxins |
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Definition
Many bugs exert their pathogen effect by producing toxins.
Antibody binds the toxins in these clumps (complexes) that then get taken out of circulation by the liver and then the toxin+antibody complexes get broken down |
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Term
| What functions of antibody does IgG do well? |
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Definition
fixes complement
opsonization for phagocytosis (excellent)
blocks attachment (because so abundant)
neutralizes toxins |
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Term
| What is notable about IgG? |
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Definition
| It passes through the placenta during the first 6 months in utero and provides early protection. IgG is passed over because it is the best at the 4 functions of antibody |
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Term
| What is agammaglobulinemia? |
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Definition
| not having enough IgG! It will be treated with iv Ig |
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Term
| What functions of antibody does IgM do well or poorly? |
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Definition
- excellent at fixing complement
- NOT good at opsonization b/c it is a pentamer, and you can't cram 5 Fc regions into the Fc receptor
- excellent at blocking attachment because it is so big |
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Term
| What is notable about IgM? |
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Definition
| It appears early in infection and wanes quickly |
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Term
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Definition
| in secretions (mucus and tears) |
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Term
| What functions of antibody does IgA do well or poorly? |
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Definition
- great at blocking attachment
- not good at fixing complement (need two variable regions 40 nm apart)
- can't opsonize for phagocytosis because need an Fc region to stick up into the receptor |
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Term
| What is notable about IgE? |
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Definition
- most people have low levels in circulation
- it binds to the Fc epsilon receptor on mast cells
- it is involved in allergic reaction |
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Term
| What functions of antibody does IgE do well or poorly? |
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Definition
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Term
| Why do IgE levels rise when infected with parasites if they aren't any good at the functions of antibody? |
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Definition
| parasitic worms drive IgE levels up so that antibodies that are good at their job (such as IgG) don't come and kill them |
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Term
| What is notable about IgD? |
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Definition
- its biological function is unknown
- it may be involved in B cell activation |
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