L13 Hypersensitivity Flashcards
What are the primary and secondary responses of the immune system?
Primary: First encounter with organism
Secondary: Sebsequent response with the same organism
What are dendritic cells?
Dendritic cells are antigen presenting cells residing in tissues.
What do dendritic cells do?
They take up antigens, become activated, and migrate to lymph nodes. Mature cells present the antigen-derived peptides on cell surface MHC molecules to activate T cells that recognise the MHC/protein combination
Which cells make up granulocytes?
Neutrophils, basophils, eosinophils, mast cells
What do neutrophils do?
Phagocytosis and degranulation
Most common WBC, can cause host damage, characterised by its nuclear lobes.
What do basophils do?
Degranulation contributes to allergic response
What do Eosinophils do?
kill parasites
What do monocytes look like and what do they do?
Large cells, horse-shoe nuclei
Phagocytosis and cytokine production, can differentiate into macrophages
What do macrophages do?
Antigen-presenting cells, oval nucleus, functionally heterogenous (can change function)
What are the adaptive cells?
T and B cells,, plasma cells, and natural killer cells
What are T and B cells characterised by?
They have a higher [nuclear] : [cytoplasm] ratio
What do plasma cells do?
Produce antibodies, differentiated from B cells, and have lots of mitochondria
What do natural killer cells do?
Cytolysis, cytokine production, has secretory lysosomes, punch holes in cells.
Describe the antibody structure
- 2 heavy and 2 light chains held together by disulphide bonds
- 2 antigen binding sites (light chain)
- Fc region: constant region, cell receptor binding
Fc receptor: receptor found on innate immune cells which bind to the Fc region.
What is hypersensitivity?
The exaggerated/inappropriate response by the immune system - mediated by IgE, IgM, and IgG, causing damage to your own body.
What does the isotope (variant) of the antibody determined by?
The heavy chains of the antibody.
What is the original antibody isotope?
IgM
What is atopy?
Atopy is the tendency to develop allergic diseases
What are the predisposing factors favouring atopic phenotype?
Genetic + environmental determinants –> triggering events –> clinical atopy upon exposure to allergen.
What are the genetic determinants favouring atopy?
- Certain alleles of HLA class II genes, PRR genes, pro-inflammatory response genes.
- Monozygotic (identical) twins are more likely to develop the same allergy than dizygotic twins
What are the environmental determinants favouring atopy?
- Excessive hygeine, decreased exposure from farm antigens, pollutants, antibiotics and vaccinations as an infant.
What are the triggering events of atopy?
- Flare ups of chronic illness, acute pathogen exposure, emotional stress, hormone fluctuations, and nutritional deficiency.
What is type 1 hypersensitivity mediated by?
IgE mediated, mast cell degranulation has many effects depending on the route of allergen entry.
What and where are the effects of hypersensitivity type 1 depending on route of entry?
gastrointestinal tract -> diarrhea, vomitting
eyes, nasal passages, and airways -> decreased airway diameter and increased mucus secretion, congestion and blockage of airways, swelling in nasal passages, ocular itching and sneezing
blood vessels -> increased blood flow, increased permeability, increased fluid in tissues causing greater flow to lymph nodes, increased effector response, hypotension potentially leading to anaphylactic shock.
