Term
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Definition
Mediated by secretion of antibody
Provides protection against extracellular microbes and their toxins.
-Block microbes from binding host cells
- Bind microbial toxins
- Eliminate microbes, toxins and infected cells from the body
- bind viruses and intracellular pathogens before they can enter host cells |
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Term
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Definition
| bind so that it can't bind (antigen) |
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Term
| Neutralization of microbes |
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Definition
Microbes use molecules in envelope or cell wall to gain entry to host cell.
Antibodies can bind to these molecules and prevent infection of host: many vaccines stimulate neutralizing antibodies |
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Term
| Neutralization of Microbial Toxins |
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Definition
Antibodies against toxins prevent toxin binding to host cell
- Emil von Behring: antibodies against diptheria toxin prevent disease
* serum therapy |
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Term
| Antibody-Dependent Cellular Cytotoxicity (ADCC) |
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Definition
Antibodis of certain IgG subclasses bind to cells (eg infected cells)
Fc regions of bound antibodies recognized by Fcy receptor on NK cells
- Nk cells activated and kill antibody-coated cells |
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Term
| IgE and Eosinophil/Mast Cell Rxns |
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Definition
IgE antibodies activate mast cell and eosinophil mediated reactions
- provide defense against helminths
- involved in allergic diseases |
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Term
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Definition
Collection of circulating & cell membrane proteins.
Plays important roles in host defense against microbes
Sequential proteolytic cleavage leading to generation of effector molecules
Three complement pathways |
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Term
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Definition
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Term
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Definition
| initiated by microbes alone |
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Term
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Definition
| initiated by microbes alone |
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Term
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Definition
C3b (or C4b) opsonizes microbes and is recognized by type 1 complement receptor (CR1) on phagocyte
- Ingestion and intracellular killing of opsonized microbes |
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Term
| Complement and inflammation |
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Definition
Small peptides released during complement activation bind to receptors on neutrophils and stimulate inflammatory reactions
- C5a, C3a, and C4a (increasing potency) |
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Term
| Evasion of Humoral Immunity by Microbes |
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Definition
Antigenic variation
Inhibition of complement activation
resistance to phagocytosis |
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