Immunology in Health and Disease Flashcards
What are the five cellular phases involved in the progression to cancer?
Normal, hyper plastic, dysplastic, neoplastic and then metastatic
What are the innate defences?
Surface barriers - skin and mucous membranes
Internal defences - phagocytes, fever, NK cells, antimicrobial proteins and inflammation
What are the adaptive defences?
Humoral immunity - B cells
Cellular immunity - T cells
What are lymphocytes?
These are a type of white blood cell that are found in the blood and lymphoid organs and these include B cells, T cells and natural killer (NK) cells
What are phagocytes?
White blood cells that can swallow and digest microscopic organisms and particles via phagocytosis
What are monocytes?
These cells circulate in the blood and then differentiate in tissues into macrophages and dendritic cells, macrophages arelocated in tissues throughout the body.
What are dendritic cells?
These are specialised cells that present antigens to the cells of the immune system
How does the innate immune system recognise foreign cells/antigens?
Innate immune system is involved in the initial screening of self and non-self antigens using pattern recognition receptors (PRRs) that recognise pathogen-associated molecular patterns (PAMPs) such as bacterial cell wall, unmethylated CpG DNA
What is the necessary first step for the activation for adaptive immunity?
Activation of specialised antigen presenting cells
What are natural killer cells?
• kills any cell that doesn’t have a MHC class I receptor (as it can’t stimulate a negative/inhibitory signal on the NK cells) and this leads to release of granules inducing apoptosis in the target cell
What form of immunity are natural killer cells a part of?
Innate immune system
How do natural killer cells work?
• kills any cell that doesn’t have a MHC class I receptor (as it can’t stimulate a negative/inhibitory signal on the NK cells) and this leads to release of granules inducing apoptosis in the target cell
How does the immune system kill cancer cells?
Cytotoxic (CD8+) T cells and helper T cells;
Cytotoxic - attach to MHC class I peptide complex and perforates membrane by enzymes and induces apoptosis
Helper (CD4+) T cells attach to class II MHC peptide complex which leads to cytokine secretion
What are the two forms of differentiated CD4+/helper T cells?
Th1 and Th2
How do Th1 and Th2 cells differ?
Th1 cells cause a cytotoxic response, Th2 cells cause an antibody response
What is the function of IFN-alpha?
This is involved in upregulating MHC class I, tumour antigens and adhesion molecules in order to promote the activity of B/T cells, macrophages and dendritic cells
What is the function of IL-2?
This is a T cell growth that binds to a specific tripartite receptor on T cells to promote their activity
What is the function of IL-12?
Promotes the activity of natural killer and T cells and is also a growth factor for B cells
What is the function of GM-CSF cytokine?
Granulocyte-monocyte colony stimulating factor– this is involved in reconstituting antigen-presenting cells
How do cancer cells avoid immune recognition?
Alter their characteristics, suppress the immune response or outpace the immune response
How may cancer cells alter their characteristics to avoid immune recognition?
Loss/down-regulation of MHC class I, down-regulation/mutation/loss of tumour antigens
How may cancer cells suppress the immune response?
Cause ineffective signals, alter cell death receptor signalling, suppress immune cytokine production
How may cancer cells outpace the immune response?
Tumour cells can simply proliferate so quickly that the immune response is not fast enough to keep their own growth in check
