Immunological processes Flashcards
How does the skin provide mechanical, chemical and microbiological barriers to infection?
Mechanical - Epithelial calls joined by tight junctions, flow of fluid, sloughing off of skin
Chemical - sebum (fatty acids, lactic acids, lysozyme), antimicrobial peptides (defensins)
Microbiological - normal flora of the skin
How does the GI tract provide mechanical, chemical and microbiological barriers to infection?
Mechanical - epithelial cells joined by tight junctions, flow of fluid, mucous, saliva
Chemical - acidity, enzymes, antimicrobial peptides (defensins)
Microbiological - normal flora of the GI tract
How does the respiratory tract provide mechanical, chemical and microbiological barriers to infection?
Mechanical - epithelial cells joined by tight junctions, flow of fluid, mucous, air flow
Chemical - lysozyme in nasal secretions, antimicrobial peptides (defensins)
Microbiological - normal flora
How does the mouth provide mechanical, chemical and microbiological barriers to infection?
Mechanical - oral mucosa
chemical - saliva
microbiological - normal flora of the mouth
What is the function of the innate immunity?
Non-specific immunity to early infection and activates the adaptive immunity
What is the function of macrophages?
Activation of endothelial cells, activation of neutrophil immigration
What is the function of dendritic cells?
Present antigens to T cells and cause differential of T cells
After establishment of a bacterial invasion, what 3 things does the innate immune response cause?
Complement activation, innate signally (activating macrophages), activation of DC
Describe morphology of neutrophil?
Multi-lobed nucleus, highly granular
What is the function of neutrophils?
Phagocytosis and activation of bacterial mechanisms
What is the complement system?
A series of serum proteins
What are the functions of the complement system?
Recruitment of inflammatory cells
Opsonisation of pathogens facilitating the uptake and killing by phagocytes
Perforation of pathogen cell membranes = lysis
List the 3 pathways that activate complement system in the order they act?
- Alternate pathways
- Lectin
- Classical pathway
What are the main cells fo the adaptive immune response?
Lymphocytes
Describe the morphology of lymphocytes?
Small WBC with large nucleus
What type of cell regulates lymphocytes?
T lymphocytes
What regulates the differentiation of lymphocytes?
Cytokines
How are T cells mutually regulated?
Increase in one type may lead to suppression of another
T cells have phenotypic plasticity, what does this mean?
They can change the type during infection depending on dynamics
What is the function of:
a) TH17
b) Treg
c) TH1
d) TH2
e) TFH
a) re-enforcement of innate immunity
b) suppression of immune responses
c) macrophage activation
d) Mast cell/B cell activation
e) B cell activation in lymph nodes
During a viral infection how is the innate immune response involved?
Production fo interferons casuistes the activation of natural killer cells which kill the infected cells
What is the function of natural killer cells?
Kill virally infected cells - suppressing the expansion of the viral infection but not clearing it
How does clearance of a viral infection occur?
Activation of adaptive immune response and increase in production of antigen specific T cells
Describe the function of TFH?
Activates B cells in the lymph nodes
a B cell takes up and presents an antigen to TFH. The T cell then activates B cell maturation by releasing cytokines
B cell matures into antibody secreting plasma cells
The cytokine released determines what antibody the plasma cell will release
What type of cell protects against intracellular bacteria like mycobacterium tuberculosis?
TH1
Describe the function of TH1 cells
Intracellular bacteria invade a macrophage in an attempt to hide from immune system
Complementary TH1 cells bind to the macrophage to activate it, the provide help for the macrophage to digest the bacterium and recruit more macrophage
What factor of the immune system do vaccines exploits?
Immunological memory
Where do memory B cells develop?
Lymph nodes
List 3 characteristics of memory B cells
Long-lived (quiescent - don’t replicate much), high affinity, class switched Ig
List 3 major issues with vaccine in medicine
Important disease with no vaccine
Long term effectiveness unknown
Vaccine uptake
What 4 things effect vaccine uptake?
Vaccine apathy - anti-vaxxers, misinformation
Practical issues - storage, transport
Economical issues - cost of manufacture, cost of transport
Herd immunity - if the majority of a population is not immune then the effort is pointless
Name 2 conditons that activate the immune system due to other wise harmless antigens, define each of these terms
Hypersensitivity reaction = inappropriate immune response to otherwise harmless extrinsic antigens
Autoimmune response = inappropriate immune response to otherwise tolerated self antigens
How are inappropriate immune reactions classified?
Type I, II, III, IV
type I is allergic reaction only
What is the end result of inappropriate immune reactions?
Inflammation and tissue destruction
What is type I reactions mediated by and what occurs?
Mast cells= hypersensitivity
what cell mediated type IV reaction?
T cells
What is the difference between primary and secondary immunodeficiency?
Primary = genetic Secondary = acquired (chemo)
List 3 types of immunotherapy?
therapeutic monoclonal antibodies
drugs
adaptive cellular immunotherapy
