Immunology and Adaptive Immunity Flashcards
How is the immune system effective in fighting off foreign bodies?
Discrimination of self from non-self
What is innate immunity?
Non-specific, instinctive, short term lasting, present from birth immunity focused around physical/chemical barriers and phagocytosis
What physical barriers are used in innate immunity?
Skin, mucociliary escalator, gastric acid, hairs, lysozymes (Destroy bacterial cell wall)
What is adaptive immunity?
Specific immunity requiring lymphocytes, memory and quicker response
What are the different examples of leucocytes?
PM Leucocytes: Neutrophils, Basophils, Eosinophils
MN Leucocytes: Monocytes, B Lymphocytes, T Lymphocytes
What are the functions of T helper cells?
T1 (CD4): Helps immune response against intracellular pathogens, secreting cytokines
T2(CD4): Helps produce antibodies against EC pathogens, secreting cytokines
What is the function of Cytotoxic T cell (CD8)?
Kills cells directly by binding to antigens, inducing apoptosis
What is the role of a T reg (FoxP3)?
Regulate immune response
What cells express MHC1 and MHC2?
MHC1: All nucleated e.g. Intracellular antigen
MHC2: Antigen presenting cells ONLY e.g. macrophage, B cells, dendritic (EC antigen)
What T cell binds to each MHC?
MCH1: Cytotoxic T cells (CD8)
MCH2: Helper T Cells (CD4)
What does a T Helper cell bind to?
A T cell receptor which is bound to antigen epitope to an MHC2 on an APC
Which interleukin is secreted when helper T cell is bound to T cell receptor?
IL-2: Binds to IL-2 receptor on T cell and produces positive feedback mechanism leading to division and differentiation
What are 3 functions of antibodies?
1) Neutralise toxins
2) Opsonisation
3) Activate classical complement system
How does a helper T cell bind to a B cell?
B cell AB binds to antigen ->Phagocytosis -> Epitope on B-cell surface bound to MHC2 -> TH2 binds to B-cells -> Cytokine secretion induces B-cell clonal expansion -> Differentiation into plasma and memory B cells
What are the most common immunoglobulins?
IgG and IgM (IgA found in breast milk/other secretions)
Which region of an antibody binds to antigens? (Which AB region to B cells?)
Fab region
Fc Region
What are 4 types of cytokines?
1) Interferons
2) Interleukins
3) Colony Stimulating Factors
4) Tumour necrosis factors
What do each of the 4 cytokines do?
1) Interferons: Produce antiviral proteins
2) Interleukins: Cell division and differentiation
3) CSF: Division and differentiation of bone marrow stem cells
4) TNF Mediates inflammation and cytotoxic reactions
What is the role of chemokines?
Chemokines attract leucocytes to sites of infection
What are the 3 main outcomes of complement system activation?
Proteins derived from the liver
1) pathogen lysis
2) Increased phagocytosis
3) Activation of leukocytes
What activates the classical complement pathway?
Antibodies
What is the classical complement pathway?
1) C1 cleaves C4 –> C4a, C4b
2) C4b binds to C2b forming C4b2b. C4b2b = C3 convertase and responsible for C3-> C3a and C3b
3) C4b2b binds to C3b forming C4b2b3b
4) C5,6,7,8,9 bind –> MAC formation
[C1 inhibitor prevents excessive activation of pathway]
