Immunology Flashcards
What is the immune system?
A network of specialised cells, tissues and soluble factors that co-operate to kill and eliminate disease causing pathogens and cancer cells
What are the 4 key features of the immune system?
1) Specifically identify and respond to ‘non-self’ or ‘abnormal self’
2) Modify response to eliminate different pathogens effectively
3) Promote active tissue repair and healing
4) Immunological memory
What can happen with an immune over reaction?
Allergy or auto immune disease
What can happen with an immune under reaction?
Cancer and infection
What is a constituative barrier and what are the 3 main ones found in the body?
A protective barrier formed by the body.
1) Skin
2) Mucus
3) Commensal bacterial
What are the adaptations of the skin to protect the body from infection?
1) Physical barrier - tightly packed, highly keratinised, multi layered cells that constantly undergo renewal and replacement
2) Low pH (5.5) and low oxygen tension (bacteria prefer a neutral/basic pH and aerobic conditions
3) Sebaceous glands which secrete hydrophobic oils, lysozyme, ammonia and antimicrobial peptides
What are the adaptations of mucus to protect the body from infection?
1) Mucus membranes line all body cavities that come int contact with the environment and they can trap invading pathogens
2) Secretory IgA prevents bacteria and virus form attaching and penetrating epithilial cells
3) Contains enzymes (lysozymes, defensins and antimicrobial peptides) which kill invading pathogens
4) Cillia directly trap pathogens and contribute to the removal of mucus assisted by sneezing etc
What does lactoferrin (found in mucus) do?
Starve invading bacteria of iron
What are the adaptations of commensal bacteria to prevent the body from infection?
1) Symbiotic relationship with host and reduce pH in colon
2) Produce bactericidins which influence other bacteria
3) compete with pathogens for nutrients
4) Synthesis vitamins (vitamin K and B12)
5) Produce antimicrobial short chain fatty acids
eradication of commensal bacteria with broad spectrum antibiotics can result in opportunistic infections. T or F?
True
Candidiasis is common
What is a primary lymphiod tissue and where are they found
Site of leukocyte development
Thymus gland and bone marrow
What is a secondary lympoid tissue and where are they found?
SIte where T and B cells are activated by antigens
Lymph nodes, spleen, adenoid (glands in roof of mouth), tonsils, peyer’s patch on small and large intestine.
What are the causes of lymphoedema and why does this increase infection risk?
Genetics, cancer treatment (removal of nodes), paracites
Pathogens are trapped in poorly draining lymph which does not pass through lymph nodes to generate an immune response
What are the 3 types of infection?
1) Acute/Limited = rapidly cleared by the immune system giving lasting immunological memory
2) Latent = controlled by the immune system but periodic episodes of pathogen reactivation and replication
3) Chronic = immune response fails (immunodefficiency) giving ongoing pathogen replication.
What is direct and indirect communication in the immune system?
Direct = receptor:ligand interactions Indirect = production and secretion of cytokines by injured or activated immune cells (autocrine, paracrine and endocrine signaling)
What is C reactive protein CRP?
Major acute phase protein in humans used as a key diagnostic marker in blood test.
Where is CRP produced and how long does it circulate for?
Rapid production in the liver
Short half life
What are the functions of CRP?
Activate the compliment system
Enhance phagocytosis by opsinisation
*Diagnosis- different serum levels are associated with different levels of inflammation
What characterises the innate immune response?
Generic and rapid
How does the innate immune system recognise a pathogen?
Pathogens express PAMPs (pathogen associated molecular patterns)
Innate immune cells express receptors for PAMPs. These are pattern recognition receptors PPR
Where are PRRs foundas part of innate immune cells?
In the cytoplasm and on the cell surface for detection of intra and extracellular pathogens
What type of leukocyte are macrophages?
Phagocyte
What type of leukocyte are natural killer cells?
Lymphocyte
What type of leukocyte are Neutrophils?
Phagocyte