Immunology Flashcards
What is innate immunity?
Non-specific immune response to pathogens
What is adaptive immunity?
Specific acquired ammunity
What cells are polymorphonuclear leukocytes?
- Neutrophil
- Eosinophil
- Basophil
What cells are mononuclear leukocytes?
- Monocytes
- T cells
- B cells
What are the cells of the immune system?
- Neutrophils (65%)
- Eosinophil (5%)
- Basophil (0.2%)
- Monocytes (5%)
- T cells (10%)
- B cells (15%)
- Mast cells
- Natural killer cells (15%)
- Dendritic cells
What are the two main types of intracellular granules that neutrophils have?
- Primary - myeloperioxidase, muramidase, acid hydrolases, proteins
- Secondary - lactoferrin, lysosome
What receptors do monocytes have on their cell wall?
- Fc
- Complement
- PRR
- Toll-like
- Mannose
- Scavenger
What receptor is expressed on eosinophils?
CD125 receptor
What is in eosin granules?
Major Basic Protein - this is toxic to helminth worms and activates neutrophils and induces histamine release from mast cells and promotes bronchospasms.
What are mast cells?
- Tissue cells which are similar to basophils
- Express IgE receptor, binding to this receptor causes degranulation of histamine
What are the four types of T cell and their role?
- T helper 1 – CD4 help immune response to intracellular pathogens
- T helper 2 – CD4 help produce antibodies to extracellular pathogens
- Cytotoxic T cell – CD8 can kill directly
- T regulatory (FoxP3 receptor) – regulate immune response and dampen the response
What receptors do B cells have?
CD19 and CD20
What cells do B cells mature into?
Plasma cells - these produce antibodies
What is the role of natural killer cells?
To recognise and kill virus infected cells and tumour cells
What are the three actions of the compliment pathway?
- Direct lysis
- Attract more leukocytes to the site of infection (chemotaxis)
- Coat invading organisms with C3b (opsonisation)
What are the 5 different types of antibodies?
- IgG
- IgA
- IgM
- IgD
- IgE
Definition of antibody
Protein produced in response to an antigen. It can only bind with the antigen that induced its formation.
Definition of antigen
Molecule that reacts with preformed antibodies and specific receptors on T and B cells
Definition of epitope
Part of an antigen that binds to the antibody/receptor binding site
Definition of affinity
Measure of the binding strength between the epitope and an antibody binding site.
What are cytokines and four examples of cytokines:
Signalling proteins secreted by immune and non-immune cells
- Interferons
- Interleukins
- Colony stimulating factors
- Tumour necrosis factor
What are chemokines?
Group of 40 proteins which direct movement of leukocytes and other cells from the blood stream to tissue or lymph organs
What components make up the innate immune system?
Anatomical barriers Mucous membranes Physiological barriers Phagocytic cells Serum proteins (complement)
What is the inflammatory process following tissue damage?
- Stop the bleeding – coagulation
- Acute inflammation – leukocyte recruitment
- Kill pathogens, neutralise toxins, limit pathogen spread
- Clear pathogens – phagocytosis
- Proliferation of cells to repair damage
- Remove blood clot and remodel the extracellular matrix
- Re-establish normal structure and function of tissue
What are the two killing pathways present in neutrophils and macrophages?
- O2 independent - lysosomes, defensins, TNF, pH
2. O2 dependent - free radicals
What is neutrophil extravasion following bacterial infection?
Movement of neutrophils from blood vessels into surrounding tissue in response to chemokine secretion from tissue macrophages
Explain the process of phagocytosis:
- Pathogen is recognised by cell surface receptors on macrophage
- Macrophage endocytoses the pathogen into a phagosome
- The phagosome fuses with a lysosome to form a phagolysosome
- Pathogen is degraded in the phagolysosome
What is passive immunisation
The transfer of preformed antibodies between humans
Two examples of passive immunisation
Transfer of maternal antibodies across the placenta
Transfer of maternal antibodies through breast milk