Wk 1 Immunology - Innate Flashcards
Hematopoietic immune cell lineages
Key differences b/w innate and adaptive immunity
What does complement recognize?
- direct recognition of bacteria
2.
What does complement cause once activated?
inflammation
pathogen destruction
What happens when innate immune cells recognize bacteria?
- Secretion of cytokines, chemokines, inflammation
- Innate effector functions: phagocytosis, degranulation, and killing of infected cells
What is complement?
Group of > 30 proteins found constitutively in plasma and interstitial fluid
-proteases in an inactive form
-become activated when exposed to pathogen surface directly or a pathogen surface bound by antibodies -> proteolytic cascade -> destruction of pathogens, innate cell function, inflammation
What cells typically produce cytokines and chemokines?
Cells of the innate immune system
What are cytokines?
Small proteins that control growth, function and/or activation of immune cells expressing the appropriate cytokine receptor
-constitutive or inducible
-innate and adaptive immune response
-communication b/w cells of immune system
What are chemokines?
A subset of cytokines that induce chemotaxis (cell movement toward high chemokine concentration)
-induce inflammation response by attracting immune cells to site of injury or infection
What are 3 key effector functions of the innate immune system?
- phagocytosis by macrophages, neutrophils and eosinophils
- degranulation by neutrophils, mast cells, basophils, eosinophils
- extraceullular DNA traps (release DNA, which is sticky to foreign antigens)
- direct cytotoxicity, NK cells release cytotoxic granules
What cells are important for anti-bacterial, anti-fungal and anti-parasitic activity?
neutrophils
macrophages (tissue only)
What cell is significant for being anti-viral?
NK cells
What cell types are anti-helminth?
eosinophils, basophils, and mast cells (tissue only)
-also allergic response induction
What is the role of dendritic cells?
- ingest foreign pathogens
- migrate to draining lymph nodes
- activate T cells in lymph nodes
Where are lymphocytes activated?
In secondary lymphoid organs - lymph nodes, spleen
What happens when CD4+ T cells are activated?
They differentiate into T helper cells (Th) and:
1. secrete cytokines
2. activate innate cells
3. activate B cells
4. anti-bacterial, -viral, fungal, parasitic
What happens when CD8+ T cells are activated?
They differentiate into cytotoxic T lymphocytes (CTL) and:
1. secrete cytokines
2. kill infected cells
3. anti-viral
Compare CD4+ and CD8+ T cell functions
How are B cells activated?
By exposure to free antigens - can be soluble proteins or surface antigens on viruses or bacteria or other pathogens
What happens when B cells are activated?
They can differentiate into plasma cells that secrete antibodies
What do antibodies secreted from plasma cells do?
- neutralize (prevent infection)
- activate innate cells
- activate complement
How do adaptive immune responses form memory?
Some activated T and B cells can persist for years as memory cells
They undergo robust and rapid re-activation upon 2nd exposure
-size and quality of adaptive response increases upon 2nd exposure
What are 2 aspects of the innate immune system that allows for immediate pathogen recognition?
- complement
- pattern recognition receptors
What do activated complement components induce?
- lysis of pathogens directly
- enhance **phagocytosis ** of pathogens by opsonization
- induce vasodilation to increase inflammation