Cell-Mediated Antiviral Immunity

Question 1

Describe macrophages

Answer 1

• Innate cells
• Phagocytic cell that consumes foreign pathogens and cancer cells - destroyed in the phagolysosome - debris is removed from the cell by exocytosis
• Broad response
• Stimulates response of other immune cells
• Migrates from blood vessels into tissues
• PRRs on the surface of the macrophage detect PAMPs

Question 2

Describe NK cells

Answer 2

• Part of the innate immunity
• Kills tumour cells and virally infected cells
• Circulates in blood and migrates into tissues
• Recognise and destroy infected cells - non-specific and no memory
• Perforins and granzymes punch holes in membranes - infected cells are lysed
• Don’t require stimulation
• Detects viral PAMPs being presented on infected cell’s surface through PRRs
• Releases cytokines to modulate the immune response and helps recruit other cells

Question 3

Describe cytotoxic T cells

Answer 3

• ‘Bridge’ between the innate and the adaptive response
• Recognise PAMPs and destroy infected cells
• Similar function to NK cells but require stimulation by dendritic cells
• Have memory - adaptive immunity
• One of the cells we try to stimulate in vaccines

Question 4

Describe dendritic cells

Answer 4

• Present antigens on its surface and triggers adaptive immunity
• Have TLRs
• Present in epithelial tissue - skin, lung and tissues of the digestive tract
• Migrates to lymph nodes upon activation - can interact with B cells and trigger antibody response
• Professional immune sensors - ingest and degrade pathogens specifically, present antigens to stimulate other immune cells and bridge innate and adaptive immunity
• Stimulate NK cells to produce granzymes and perforins
• Induce NK cell proliferation
• Induce cytokine secretion in NK cells
• Activate T cells
• Secrete cytokines to recruit immune cells to the site of infection