Immuno Flashcards
Immune system
cells, tissues, and molecules that mediate resistance to foreign elements (antigens)
Immune response
reaction of cells and molecules to antigens
Immunology
study of immune system, response to pathogens + its role in disease
Antigen
- antibody generator
- induces immune response when introduced to the body
Epitope
Also called antigenic determinant
- part of an antigen, induces immune response and binds to products (lymphocyte receptors and antibodies)
Autoimmunity
failure to discriminate foreign elements from components of its own (self vs non self)
What are the 2 types of immune defense?
- Innate (non specific)
- Adaptive (specific)
Innate immunity
physical barriers, inflammation, and complement system
- always active
- macrophages, neutrophils, NK cells
- Fast response
- No memory cells
Adaptive immunity
Humoral and Cellular immunity
-active when in contact with antigens
- T + B cells
- Slow response
- specifically unique to each pathogen
- memory cells are present
Ex: a vaccine takes time to develop immunity
PAMPs
components shared between dif types of pathogens and present a molecular composition that differs from “self”
DAMPs
- Intracellular DAMPs = released when cells die
- Extracellular DAMPs = generated when CT is damaged
Pattern Recognition Receptors (PRRs)
receptors of INNATE immunity that recognizes PAMPs and DAMPs
- soluble or membrane bound
- signalling or phagocytic
Neutrophils
- Located in blood
- 48-72 hr life span
Function: antimicrobial effectors in acute bacterial infection
Action: phagocytosis, degranulation, extracellular trap mechanism
Eosinophils
Located in blood + tissues of GI tract + airways
- survives days to weeks
Function: antiparasitic effectors in helminthic infection, antiviral action, roles in allergy
Action: Degranulation, some phagocytosis
Basophils
Located in blood
- Survives days
Function: mediator of inflammation
Action: Degranulation
Which immune cells action is degranulation?
- Basophils
- Eosinophils
- Neutrophils
- Mast cells
Mast cells
Located in CT surrounding vasculature + lamina propria of mucose
- Survives weeks to months
Function: immune surveillance, mediator and amplifier of inflammation and allergy
Action: Detects threats + release of inflamm. mediators by degranulation or synthesis of lipid mediators and cytokines
releases histamine and serotonin (VASCULAR amines)
Macrophages
Located in peripheral tissues, survives months
Function: immune surveillance, antimicrobial capacity, some antigen presentation (adaptive immunity)
Action: Detects threats and release of inflamm. mediators, phagocytosis
Dendritic cells
Located in tissues, survives months, needed for adaptive immunity
Function: immune surveillance, antigen processing and presentation
Action: detects threats and release of inflamm. mediators, endocytosis + phagocytosis
Natural Killer (NK) cells
Located in blood + spleen, survives months
Function: Destruction of viruses and tumor cells
Action: Recognizing virally infected/abnormal host, target release of CYTOTOXIC GRANULES
Lymphocytes
Located in blood, tissues, and secondary lymphoid organs (spleen)
Survives weeks to months to years (memory cells)
Ex: T + B cells
Complement system
Plasma proteins (proteolytic) that are inert but can interact in cascade once activated
Attacks cell membrane leading to death
Signalling molecules that recruit immune cells to inflamm. sites
3 Pathways: Alternative, Classical, Lectin
Receptors in immune system
On surface or in intracellular compartments
Ligands in immune system
molecules that activate receptors
Soluble or membrane bound
Cytokines
proteins for cell growth + activation
Ex: Interleukins- communication between cells
Ex: Chemokines- chemotaxis
Sentinel cells
- Dendritic cells
- Macrophages
- Mast cells
- Releases pro-inflammatory + antimicrobial mediators
- Activates innate response
- Many receptors for PAMPs and DAMPs
Leukocyte extravasation
- Selectins - rolling
- Integrins - adhesion
- Chemokines - migration through endothelium
Reactive oxygen species (ROS) and Reactive nitrogen species (RNS)
OXIDATIVE PATHWAY OF KILLING
Uses oxygen and glucose to increase several fold “respiratory burst”
Toxic to microorganisms
Cationic proteins
Damage bacterial cell wall
Lysozyme
Damages mucopeptides in bacterial cell wall
Lactoferrin
sequestrates iron, inhibits baterial growth
Proteolytic + Hydrolytic enzymes
digest killed bacteria
Non oxidative pathway of killing?
Depends on action of toxic substances in lysosomes
- Cationic proteins
- Lysozymes
- Lactoferrin
- Proteolytic + hydrolytic enzymes
Neutrophil Extracellular traps (NETs)
Extrudes strands of DNA and proteins into ECF
Traps + kills microbes
Alternative pathway
- Complement proteins activated on microbial surface
- Needs microbe, innate immunity
Lectin pathway
Activated when a carb-binding protein, mannose binding lectin (MBL), binds to terminal mannose on glycoprotein surface
- Innate immunity
Classical pathway
- Adaptive immunity
- Activated by antibodies that bind microbes or antigens
What is the end result of the Alternative, Lectin, and Classical pathway?
Membrane attack complex (MAC)- osmotic lysis
Membrane attack complex
Breaches membrane of microbe, allowing water to rush into cell
Destruction by osmotic lysis (swells and dies)
Ig Isotypes
IgM- blood
IgG- Blood + tissues
IgA- mucous membranes
IgE- Epithelial tissue
Humoral response
Primary Ig isotype to respond? Secondary?
Primary- IgM
Secondary- IgG
MHC 1
presents antigens to CD8+ T cells
All nucleated cells, free in cytosol
Can kill any type of virus infected cell
MHC 2
Presents antigens to CD4+ T cells
Helper T cells!
Endocytosis of extracellular protein
Professional antigen presenting cells (Dendritic, Macrophages, B cells)
How are Naive T cells activated?
Dendritic cells
- Proliferation
- Differentiation
CD4+
Th1, Th2, Th17
Helper T cells
Secretes cytokines that activate other cells
Presented by MHC 2
CD8+
Cytotoxic T cells
Kills infected cells, induces apoptosis
Presented by MHC 1
CD4+ Th1 cells
Cytokine secretion
Activates macrophages and CTLs (CD8+)
