Flashcards in Week 8 - Cells and Tissues of the Immune system Deck (16)
What are five components of innate immunity?
Epithelial barriers, dendritic cells, phagocytes, complement cascade and NK cells
How many days after infection do we see antibodies from B cells and Effector T cells?
What do macrophages and dendritic cells do?
They are phagocytic cell and professional antigen presenting cells. They recognise MAMPS via PRRs (pattern recognition receptors)
What role do epithelial cells play in the innate immune system?
They are sentinel cells, recognising MAMPS and responding with inflammatory mediators
What do natural killer cells do?
Kill damaged or virus infected cells, in an action similar to cytotoxic T cells
What happens with MAMPS are recognised by PRRs?
PRRs induce endocytic activation and signal transduction, turning on immune mediator production and/or phagocytosis. This causes antigen capture, phagocytosis, opsonization, antigen presentation, complement activation, kinin production, cytokine response, removal of pathogens cytolytic killing of pathogens and activates adaptive immunity
What are the six main cells of the adaptive immune system?
Antigen-presenting cells: capture, digest and present epitopes to T cells, activating adaptive immunity
B cells - produce and secrete antibodies
Plasma cells - Activated B cells, producing antibodies
T-Helper cells - Help B cells produce antibodies, help macrophages kill bacteria, and promote or suppress other immune functions
T-regulatory cells - Active suppression of immune responses, tolerance
Cytotoxic T-cells - detect and kill infected cells
Which cells recognise a pathogen in the adaptive immune system?
TCRs and BCRs. Each B and T cell will express a unique receptor
What are the differences in speed of response in innate vs adaptive immune system?
Innate: quick acting all the time, broad specificity
Adaptive: relatively slow on first exposure to antigen, quick for following exposures. Highly specific
What are the four professional antigen presenting cells, and why are they called professional?
Monocytes, macrophages, B cells and dendritic cells
Professional because they present the antigen to the TCR via the MCH class II molecule Other cells don't use class II, they use class I.
What are the differences in roles between primary and secondary lymphoid organis?
Primary: develop and mature lymphocytes. Bone marrow is the main precursor of B and T cells, and these go to the thymus for development
Secondary: trap antigens, are sites that lymphocytes can effectively interact with these antigens. these include lymph nodes, spleen appendix and tonsils
What happens in central tolerance?
The thymus displays peripheral tissue antigens in the thymic medullary epithelial cells. Lymphocytes move past these, and if they recognise 'self', they are signalled for apoptosis.
What is humoral immunity mediated by?
Macromolecules. It is found in extracellular fluids i.e. secreted antibodies, complement proteins and certain antimicrobial peptides
How are B cells activated?
Activation is initiated by specific recognition of antigens on the surface Ig receptors of the B cells. The recognition of the antigen, along with T-helper cells, stimulates the proliferation and differentiated of the specific B cell clone. Progeny of the clone may produce antibodies, undergo affinity maturation, or persist as memory cells
What are the five T-helper subsets?
Th1 - protects against intracellular pathogens
Th2 - protects against extracellular pathogens
Th17 - protects against extracellular pathogens
Treg - Immunosuppression
T follicular helper cells - trigger and maintain germinal centres