Intro to Immunology Flashcards
What are the 3 main compartments of the immune system?
Physical barriers
Innate immune system
Adaptive immune system
What are the innate immune cells?
Mast cells NK cells Basophils, neutrophils, eosinophils, monocytes Macrophages Dendritic cells
Name 4 differences between innate and adaptive immune system?
Adaptive - more specific, takes longer, good memory, cell-mediated
Innate - faster, present at birth, no memory
What physical/chemical barriers exist in the respiratory tract?
Mucous + mucociliary escalator Alveolar surfactant Epithelial cells as barrier Nose hairs Enzymes in mucous
Which innate immune cells are present in tissues?
Macrophages
Dendritic cells
Mast cells
What are the innate cells?
NK cells Dendritic cells Macrophages Basophils Eosinophils Neutrophils
Monocytes form what cells?
Macrophage
Dendritic cells
How do tissue cells recognise foreign substances?
Antigen receptor sites
How do macrophages signal the presence of foreign substances?
Cytokines
Give 3 functions of the innate immune system?
Inflammation Recruit other cells Activate complement Phagocytosis Opsonisation
What is required to help bind immune cells to an infected site?
Adhesion molecules to allow ‘sticking’ to the endothelium
Why do macrophages find it difficult to consume mycobacterium?
Waxy coat
Catalase enzyme
What is the signalling role of macrophages and dendritic cells?
Antigen presentation with MHC 1 and 2 to T cells
What are antibodies made of?
Glycoproteins
What is an antigen?
Molecule capable of inducing an immune response
What produces antibodies?
B lymphocytes
Where is MHC I located?
All nucleated cells and platelets
MHC II presents to what?
CD4 cells
Where is MHC II located?
ONLY antigen presenting cells
MHC I presents to what
CD8 cells
Where do T cells mature?
Thymus
CD4+ T cells to proliferate into what in exposure to MHC II?
Helper T cells
CD8+ T cells to proliferate into what in exposure to MHC I?
Cytotoxic T cells
What is required for response by CD4+ T cells?
MHC Class II
What are the key cells of the adaptive immune system?
B and T cells
How do Dendritic cells function?
Sentinel - activate adaptive immune system
Internalise pathogen, break it down into peptides
Presents peptides (antibodies)
Activates naive T cells
Th1 cells signal with which cytokine?
Interferon gamma (y)
Th2 cells signal with which cytokine?
IL-4,5,13
Th17 cells signal with which cytokine?
IL-17, 22
What is the role of Th1 cells?
Activate macrophage
Produce IgG
Fight intracellular microbes
Autoimmune disease
What is the role of Th2 cells?
Activate mast cells, eosinophils
Produce IgE
Parasites
Allergies
What is the role of Th17 cells?
Neutrophilic/monocytic inflammation
Extracellular bacteria, fungi
Autoimmune inflammation
How do T helper cells facilitate activation of other immune cells?
Cytokines
When are cytokines produced?
Normally
In response to microbes or tissue damage
What produces cytokines?
T (helper) cells
Macrophages
How to CD4 cells help naive CD8 cells?
CD4 aids in response to peptides presented with MHC I
How do CD8+ (cytotoxic) T cells kill target cells?
Perforin - puncture cells
Granzyme - induces apoptosis
What are the main cells of direct killing of pathogens?
Cytotoxic (CD8+) T cells
NK cells
What is the role of NK cells in preventing cancer?
Cancer decreases MHC I expression
NK cells will bind to cells with low MHC I expression and release Perforin and Granzyme
Trigger apoptosis
What is the result of B cell activation?
Antibody secretion
What does the fab portion of an antibody do?
Variable - binds to particular antigen
What does the Fc portion fo an antibody do?
Bind to Fc receptors on normal cells (to fix)
What are the Ig classes? What structure do they form?
IgM (Pentamer) IgG IgA (Dimer) IgE IgD (Rest monomer)
What is unique about IgM?
Pentamer
Best at activating complement
What is unique about IgG?
Can cross placenta
What is unique about IgA?
Dimer
Contained in secretions
What is unique about IgE?
Role in parasitic infections and allergies
When are IgM produced?
As fetus
When are IgA produced?
Breast milk consumption
At 1-2 months post birth
How do B cells respond to infection??
Can present antigens
Cytokine production
B memory cells
Plasma cell formation - antibodies
What are the functions of antibodies?
Neutralisation Opsonisation and phagocytosis Complement activation Inflammation Antibody dependent cellular cytotoxicity (NK cells)
How does antibody mediated immunity vary with time/exposure?
First response - Large IgM response then moderate IgG
Second response - small IgM response then huge IgG response
What is Opsonisation?
Reduce repellent negative charge of cell
Increases binding sites
What are the main opsonins?
Complement C3b, C4b
Antibodies
plasma proteins
What are the stages of complement activation?
- Chemotaxis (phagocytes to inflammation site)
- Opsonisation
- Lysis
- Maintain Complex solubility
