Week 9 immunity & inflammation Flashcards
2 divisions of immunity
- Innate immunity
2. Adaptive immunity
3 Levels of innate immunity
- Defence barrier
- Cellular - phagocytes and NK cells
- Humoral - soluble factors
3 Types of soluble factors
- Acute phase protein
- Complements
- Interferons
3 Functions of complements
- Cytolysis
- Chemotaxis - attract phagocytes
- Opsonization
4 steps of phagocytosis
- Chemotaxis
- Adherence
- Ingestion
- Digestion
Receptors that neutrophils and macrophages are equipped with
Pattern Recognition receptors (PRRs):
for recognition of pathogens
Functions of neutrophils and macrophages
Neutrophils
- Phagocytosis
- Production of anti-microbial proteins
- Secretion of inflammatory cytokines
Macrophages:
- Phagocytosis
- Production of free radicals: toxic to bacteria and intracellular parasites
- Secretion of pro-inflammatory cytokines
Main Function of Natural Killer Cells
Substance present inside NK cell
- Kill cancer cells or virus-infected cells
- Secrete cytokines
Contains
Cytotoxic granules with perforins (pore-forming protein) and granzymes (promote apoptosis)
Receptors possessed by NK cells
- Killer activating receptor (KAR)
2. Killer inhibitory receptor (KIR)
4 Effector Functions of complement proteins
- Opsonization
- Chemotaxis
- Cytolysis: attack membrane
- Inflammation
Definition of cytokines
An important type of cytokine in immune function
Proteins made by cells that can module behaviour/function/differentiation of other cells
Important type:
interferons
Functions of interferons
- Suppress viral replication in infected cells -> limit viral spread
- Activate other immune cells -> enhance viral clearance
2 Arms of adaptive immunity
- Humoral immunity
2. Cell-mediated immunity
What are primary and secondary lymphoid organs?
Give an example of each
Primary lymphoid organs:
for development and maturation of lymphocytes
(e.g. thymus, bone marrow)
Secondary lymphoid organs:
for differentiation of lymphocytes
(e.g. spleen, lymph nodes)
What are immunoglobin and its basic structure?
Antibodies
Basic structure:
2 light chains and 2 heavy chains
-> Variable region (Fab)
-> Constant region (Fc)
Major effector functions of B cells
- Production of antigen-specific antibodies
2. Production of cytokines
Functions of T cells which class of MHC molecules does it recognize?
CD8+ (cytotoxic T cell):
recognize peptide on MHC class I on antigen-presenting cell
mediate cytotoxic killing of antigen-specific target cell
CD4+ (helper T cell): recognize peptide on MHC class II produce cytokines -> modulate functions of other immune cells
3 Phases of adaptive immunity
- Recognition
- Activation
- Reaction
4 General Functions of B cells
- Neutraliziation
- Opsonization
- Complement activation
- Antibody-dependent cellular cytotoxicity
5 signs of inflammation
- Redness
- Swelling
- Pain
- Loss of function
- Heat
3 Outcomes of acute inflammation
- Resolution
- Healing by scar
- Progression into chronic inflammation
4 Characteristics of adaptive immunity
- Antigen specific
- Diverse repertoire
- Immunological memory
- Self and non-self discrimination
3 Major differences between primary and secondary responses
- Time of induction
- Magnitude of reaction
- Decline in reaction after reaction phase
2 levels of self and non-self discrimination
- Central tolerance:
deletion of self-reactive T/B cells in primary lymphoid organ - Peripheral tolerance:
deletion(apoptosis)/inactivation (anergy)/suppression of self-reactive T/B cells in secondary lymphoid organs
Components involved in acute inflammation
- Tissue damage
- Chemical mediators
- Blood vessels
- Neutrophils
2 Categories of chemical mediators released during acute inflammation
- Cell-derived mediators (e.g. histamine from mast cell)
2. Plasma protein-derived mediators (e.g. complement system)
How do vasodilation and increased vascular permeability help in inflammation?
Vasodilation:
Facilitates migration of neutrophils out of blood vessels by moving them to peripheral zone (margination) as vessel is packed with slow-moving RBC
Increased vascular permeability:
- Immunoglobins move to damaged tissues
- Coagulation proteins move into tissue for blood clot formation
How do neutrophils reach injury site?
1. Leave blood vessel adhesion molecules (selectin and integrin) stick leukocytes to endothelial cells -> emigration
- Move to site of injury by chemotaxis
Neutrophils recognize concentration gradient of chemoattractants -> move by amoeboid movement
What are chemokines?
small proteins that can cause migration of cells
4 Common causes of acute inflammation
- Physical agent - burn
- Biological agent - bacteria, fungi
- Chemical agents
- Hypersensitivity
4 Functions of monocytes (macrophages)
- Phagocytosis
- Antigen presentation
- Secretion of mediators
- Induction of general effects
What are antigens
Cellular structures that induce immune responses
Composition of fungal cell membrane
Ergosterol
3 classifications of fungus
- Yeast - unicellular
- Mould - multicellular
- Dimorphic fungi -
yeast at 37oC
mould at 25oC
4 Histological hallmarks of chronic inflammation
- Infiltration of mononuclear inflammatory cells
- Granulation tissue
- Tissue destruction and fibrosis
- Regeneration
What is granulomatous inflammation?
A special type of chronic inflammation
Characterized by formation of granuloma - collection of modified macrophages called ‘epitheloid cells’
