1. Intro To Immunlogy Flashcards
LOs
- Provide a historical perspective of immunology
- Define the term “immune system” and “immunity”
- Describe in outline the cells of the immune system
- Describe where immunity is induced
- Describe the immune strategies of the host
- Distinguish between innate and adaptive immunity
what is the immune system?
- Vast communication network of cells +
chemical signals distributed in blood +
tissues throughout the human body - regulates normal growth and development of
the organism while protecting against disease
cells of the immune system
Where is the immune system?
- lymphatic system (specific areas)
- all cells made in bone marrow
- B cells go to secondary lymphoid organs
- T cells go to thymus
where is the immune response generated?
- secondary lymphoid organs + tissues
what is immunity?
- Condition/process in humans that permits
innate and acquired resistance to disease - host needs to recognise non-self (microbes) components & eliminate them
Requirements for effective immune system?
- Must recognise wide range of infectious
microorganisms including “new” ones - Defend against both intracellular and
extracellular pathogens (tolerate commensals) - Prevent or limit damage to self
- Respond quickly
Routes of Exposure to Infectious Microbes?
infections are often specific
SKIN
~ External surfaces (athlete’s foot – fungus)
~ Insect bites (malaria, Lyme)
~ Trauma (tetanus)
MUCOSAL MEMBRANES
~ Inhalation (tuberculosis)
~Gastrointestinal tract (hepatitis A)
~Reproductive tract (HIV, syphilis)
2 main types of immunity
- INNATE IMMUNITY
~ Non-specific
~ Immediate - ADAPTIVE IMMUNITY
~ Specific
~ Delayed
How does an infection evolve?
Innate Immunity: Epithelial barriers
hint
- mechanical
- chem
- microbiological
MORE EGs
- 1L/ day mucus
- mechanical washing expulsion (coughing/ sneeze)
- AMP-defensins, histatins, cathelicidin
Innate Immunity: Complement activation pathways?
- classical pathway
- MB-lectin pathway
- alternative pathway
what do phagocytic cells do? (innate immunity)
Cells that “consume/eat” their enemy
programmed to recognise, eat, destroy
phagocytic cells EGs
14 amin ones BUT these most important
- monocytes (in blood)
- neutrophils (in blood) (IMPORTANT)
- macrophages (in tissue) (IMPORTANT)
- dendritic cells (in tissues and blood)
process of phagocytosis?
- RECRUITED to site of infection: chemokines (compliment)
- BINDS microbe - pattern recognition, opsonisation (C’/Ab)
- INTERNALISES microbe (phagocytosis) - phagosome
- fusion of phagosome with lysosome - phagolysosome
- killing of microbe : nitrogen oxides, oxygen products
innate immunity key points
- physical barrier (eg epithelium)
- natural humoral components (eg antimicrobial etc) (in solution eg blood)
- recruitment + activation of phagocytic cells (pattern recognition receptors)
- activation of adaptive immunity (T+B cells)
what bridges innate and adaptive immunity
Phagocytic cell – dendritic cell (antigen presenting cell)
- Present in blood and tissues
- Capture microbe
- To lymph node to induce ADAPTIVE immunity
what is a dendritic cell?
Antigen presenting cells
MAKE QS
- Microbes are digested into small peptide fragments (processing)
- Antigen are presented on (presentation):
~ MHC class I molecules (internal pathogens,
viral) or
~ MHC class II molecules (external pathogens,
bacteria) - MHC/peptide complex taken to surface and presented to T cells:
~ MHC class I - CD8+ T cells (cytotoxic T cells)
~ MHC class II - CD4+ T cells (T helper cells)
ADAPTIVE IMMUNITY
- mediated by?
- main cells involved
- what do the main cells involved do?
- restricted to vertebrates
1
lymphocytes
2
* T cells – helper and cytotoxic
* B cells - antibody
3
- T and B cells generate an immunologic response that specifically targets that pathogen and generates memory for future protection
lymph node structure (need to know???)
T LYMPHOCYTES
- 2 main types?
- mechanism of Tc killing
- what happens after CD4+ Th cell activation?
1
- CD4+ T cells (T helper cells: Th)
- CD8+ T cells (T cytotoxic cells: Tc)
2
- cytotoxic T cell recognises complex of viral peptide with MHC class I and kills infected cell
3
1. proliferation
2. differentiation into effectors
3. effector functions
Antibody (IgG) structure
- Antibody or Immunoglobulin (different flavours)
- Y-shaped protein molecule (Fc and Fab)
- Neutralise unwanted invaders
Timeline of adaptive immune response
Summary
- Innate Immunity
- Adaptive Immunity
- Signalling molecules
- INNATE IMMUNITY
- Physical barrier (skin, epithelium)
- Rapid response
- Minimal specificity
- Humoral components
(antimicrobial peptides, complement) - Pathogen recognition
- Phagocytosis
- Activation of adaptive immunity
- ADAPTIVE IMMUNITY
* Mediated by T and B cells
* Long term response
* Highly specific
* Memory (fast second response) - SIGNALLING MOLECULES
* Chemokines
* Cytokines
