OE L21 Basic Immunology Flashcards
(38 cards)
Where do T and B cells develop?
T cells: thymus
B cells: bone marrow
What 2 responses is host immunity divided into?
- Innate immunity (non-specific)
- Adaptive immunity (antigen-specific)
Describe the main features of innate immunity.
- Non-specific
- Fast response
- First line of defence
- No memory
- Alarms and intiates adaptive immunity
What are the cell types involved in innate immunity?
- Epithelial cells of mucosa and dermis
- Endothelial cells
- Fibroblasts
- Phagocytes
- Natural killer cells
- Innate lymphoid cells
- Innate T cells
Describe the role of mucosal epithelial cells in innate immunity.
- Tight cell junctions = strong physical barrier
- Produce cytokines and chemokines in response to pathogens damaging this barrier
Describe the role of fibroblast cells in innate immunity.
- Present in the lamina propria
- Produce collagen to aid tissue repair
- Can prevent pathogens penetrating deeper
- Recruit other immune cells in repsonse to bacterial products
Describe the role of neutrophils in innate immunity.
- Produced and secreted in response to chemokines
- Phagocytic activity
- Produce ROS and RNS (reacitve oxygen/nitrogen species)
- Produce enzymes, e.g. MMPs, to facilitate immune cell infiltration
Describe the role of macrophages in innate immunity.
- Migrate to site of infection in repsponse to chemokines
- Phagocytic activity
- Produce ROS, RNS, enzymes and antimicrobial peptides
- Produce cytokines to signal to immune system and recruit more immune cells
Describe the role of dendritic cells in innate immunity.
- Phagocytic activity
- Take pathogens, migrate them to draining lymph nodes to activate adapative immune response - act as antigen presenting cells
Describe the role of mast cells, basophils and eosinophils in innate immunity.
- Produce histamine
- Dilates BVs to allow more immune cells and serum to infection site - causes swelling
- Phagocytic activity
Describe the role of natural killer cells in innate immunity.
- Important in viral infection and cancers
Describe the role of innate T cells in innate immunity.
- Belonging to T cell group
- Do not recognise specific antigens
- Has a T cell receptor of gamma delta chains
Describe the role of innate lymphoid cells in innate immunity.
- Abundant in intestinal mucousal
- Mainly involved in immunity of mucosa
How do innate immune cells recognise pathogens?
Innate immine cells have PRRs on their intra or extracellular cell surfaces- pattern recognition receptors.
What are the 4 major groups of PRRs?
- TLRs: toll like receptors
- CLRs: c-type lectin receptors
- NLRs: NOD like receptors
- RLRs: RIG like receptors
Describe the main features of adaptive immunity.
- Slow development
- Specific
- Has memory
- Long lasting
- Initiated by dendritic cells (antigen presenting cells)
Where do T and B cells mature, and where do they then travel to?
T cells mature in the thymus, B cells in the bone marrow.
Travel to lymph nodes and spleen where they remain until immune system is triggered and they’re required.
Describe the structure of a lymph node in relation to the immune cells.
- Have a T cell zone (most inner zone)
- Have a B cell zone
Germinal centres in B cell zone where B cell proliferation and maturation takes place.
What is the B cell marker?
CD19.
- B cells develop in bone marrow
- Antibody producing cells
- Humoral immunity (antibody mediated immune response)
What is the T cell marker?
CD3.
- T cells develop in thymus
- Produce cytotoxic cells and T helper cells
- Cell mediated immune response
What are the 3 functions of B cells?
- Antibody production
- Presentation of antigens to T cells
- Cytokine production
Each naive B cell expresses a B-cell receptor, what happens when an antigen binds to this receptor?
The B cell undergoes proliferation and matures into an antibody producing cell as well as producing memory B cells.
What are the functions of antibodies?
- Block entry of virus into cells
- Neutralise toxic domain of pathogens
- Aggregation causes soluble antigens to become insoluble
- IgG is an opsonin so makes pathogens more susceptible to phagocytosis
What are the 5 major antibodies in humans and briefly describe each one.
- IgA: found in saliva as a secretory antibody
- IgD: cell surface antibody serves as B cell receptor
- IgE: antigen binding can trigger histamine release from mast cell
- IgM: produced at early stage of infection, isotype switch to IgG
- IgG: most stable antibody in serum and involved in immune memory
