IM1: Cells of the Immune System Flashcards
What are the 3 types of granulocytes?
- Neutrophil
- Eosinophil
- Basophil
Which granulocyte is the most numerous innate immune cell?
Neutrophil
Which granulocytes is involved in allergic reactions? (2)
- Eosinophil
- Basophil
What are mast cells and where are they found?
Mast cells can mediate allergic reactions by releasing inflammatory chemicals like histamine. These cells are found in tissues
What are the precursors of macrophages? Where are these macrophages found?
- Monocytes
- Bloodstream and in tissues
What are some important non-immune functions of macrophages? (2)
- Recycling dead cells (ie RBCs)
- Clearing away cellular debris
Explain the neutrophil and macrophage response to local injury
- Neutrophils accumulate at sites of local tissue injury
- They then communicate with each other using lipid and other secreted mediators to form cellular swarms.
- Signals coordinate macrophages to surround neutrophil cluster to form a tight wound seal
What type of immune cell is a dendritic cell?
What cell do they develop from?
- Antigen presenting cell
- Monocytes
Which cells recognise antigens on APCs? (2)
- Adaptive B cells
- T cells
What are the importance of MHC molecules in dendritic cells? (2)
MHC provides a checkpoint and helps immune cells distinguish between host and foreign cells
Which MHC molecule is involved in intracellular antigens?
MHC-I
Which MHC molecule is involved in extracellular antigens?
MHC-II
How do NK cells kill virus-infected cells or tumour cells?
- They contain intracellular compartments called granules
- Filled with proteins that can form holes in the target cell
- Causing apoptosis
What are some key differences between apoptosis and necrosis?
- Apoptosis does not release danger signals
- Through apoptosis, immune cells can discreetly remove infected cells and limit bystander damage
What are the 2 major functions of B cells?
- They present antigens to T cells
- Produce antibodies to neutralize infectious microbes and the toxins produced by them
What are the 3 main functions of antibodies?
- Neutralisation
- Opsonisation
- Complement (directly destroying bacteria)
What are the 2 ways B cells express antibodies?
- The B Cell receptor is an antibody in itself
- B cells secrete antibodies that are soluble
What are 2 major functions of T cells?
- Killing infected cells
- Activating/Recruiting other immune cells
Give an example of cytotoxic T cells
- CD8+ T cells
- CD4+ T cells
How do cytotoxic T cells remove infected cells?
Once bound to the infected cell cytotoxic T cells release cytotoxins causing apoptosis
What are the four major CD4+ T-cell subsets
- TH1
- TH2
- TH17
- Treg
What is the function of TH1 cells?
Coordinate immune responses against intracellular microbes. They produce and secrete molecules that alert and activate other immune cells.
What is the function of TH2 cells?
Coordinate immune responses against extracellular pathogens by alerting B cells, granulocytes, and mast cells
What is the function of TH17 cells?
Produce IL-17 which activates immune and non- immune cells
What is the function of Treg cells?
Monitor and inhibit the activity of other T cells
The molecules that activate receptors are called?
Ligands
How can immune cells communicate? (2)
- Cell-to-cell contact
- Secreted signalling molecules (ligands)
What do type I interferons do?
Mediate antiviral immune responses
What do type II interferons do?
Important for antibacterial responses
What do interleukins do?
Provide context-specific instructions, with activating or inhibitory responses for immune cells
Give an examples of colony-stimulating factors (2)
- Interferons
- Interleukins
What do tumour necrosis factor (TNF) stimulate?
Immune-cell proliferation and activation
Where are Toll-like receptors found?
What is their function?
- Expressed on innate immune cells, like macrophages and dendritic cells
- Innate immune-cell activation and inflammatory responses
What is the benefit of the genes for BCRs/TCRs randomly being rearranged at specific stages of cell maturation?
Results in unique receptors that potentially may recognise anything
What is the functions of MHC-I proteins?
Which cells are they expressed in?
Linked with which T cell?
- Present viral antigens
- All cells besides RBCs
- CD8+ T cells
What is the functions of MHC-II proteins?
Which cells are they expressed in?
Linked with which T cell?
- Present viral antigens
- APCs like dendritic cells and macrophages
- CD4+ T cells
