Term
| What is antibody feedback? |
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Definition
| Binding of IgG/antigen complex to the B cell which results in inactivation as a means to regulate activity |
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Term
| What can affect the nature of T cell and B cell immune responses? |
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Definition
| The ratio of TH1 and TH2 cells |
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Term
| What determines activation of TH1 generation by dendritic cells? |
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Definition
| Viruses and some bacteria induce IL-12 secretion by dendritic cells that can activate NK cells to produce IFN-y and stimulate CD4 cells to become TH1 |
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Term
| What determines activation of TH2 generation by dendritic cells? |
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Definition
| Other pathogens like worms do not induce IL-12 expression in dendritic cells but may cause NK1.1+ T cells to synthesize and secrete IL-4, stimulating CD4 T cells to become TH2 |
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Term
| How do APCs stimulate formation of TH2? |
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Definition
| Presentation of a weakly-binding peptide to the TCR will result in TH2 formation |
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Term
| How do APCs stimulate formation of TH1? |
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Definition
| Presentation of a strongly-binding peptide to the TCR will result in TH1 formation |
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Term
| How do TH1 and TH2 negatively regulate each other? |
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Definition
TH1 secretes IFN-y, which inhibits TH2 proliferation
TH2 secretes TGF-b and IL-10, which inhibit activation and growth of TH1 |
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Term
| What are four tolerance mechanisms, and what are the results? |
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Definition
1) Clonal deletion --> death
2) Clonal anergy --> loss of function
3) Receptor editing by RAGS --> change of receptor specificity
4) Active suppression --> loss of function |
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Term
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Definition
| When an immature lymphocyte receives signal one without signal two (NOT the other way around) |
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Term
| How are autoreactive T cells suppressed? |
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Definition
| Regulatory T cells (Tregs) on the same antigen presenting cell can suppress autoreactive T cells |
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Term
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Definition
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Term
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Definition
| Deficiency in transcriptional repressor FoxP3 causes a lack of functional Tregs. Fatal autoimmunity develops to the gut, endocrine, and skin |
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Term
| What happens when immune regulation fails? |
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Definition
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Term
| What autoimmune reaction occurs in type 1 diabetes? |
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Definition
| Effector T cells recognize peptides from a b cell-specific protein and kills the b cell |
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Term
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Definition
| Autoimmune regulator gene, a protein transcription factor which induce expression of 100s of genes that encode proteins normally only expressed by one or a few peripheral tissues |
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Term
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Definition
| By thymus epithelial cells in the thymic medulla |
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Term
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Definition
| Patients have defective Aire alleles and develop T and B responses to self antigens |
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Term
| What other factors are associated with autoimmunity? |
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Definition
| HLA allotype, genetic variation in the peptide-binding region of MHC |
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Term
| What is sympathetic ophthalmia? |
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Definition
| A loss of tolerance where trauma to an eye results in release of sequestered intraocular protein antigens and subsequent activation and migration of effector T cells, which attack antigen in both eyes |
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Term
| How does rheumatic fever occur? |
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Definition
| Streptococcal cell wall stimulates an antibody response, but some antibodies cross-react with heart tissue, causing rheumatic fever |
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Term
| What is epitope spreading? |
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Definition
| Lack of tolerance of CD4 T-cells to a nuclear component leads to many self-active B cells (Each T cell can activate several B cells) |
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