Overview of immunology Flashcards
Antigen
Anything the immune system responds to
Usually protein
Not necessarily bad
Antigen receptor
Recognises the antigen
Fundamental basis of immunity
Basis of division into innate and adaptive
Myeloid lineage functions
Neutrophil: phagocytosis
Eosinophil: helminth infections
Monocyte/ macrophage: phagocytosis, antigen presentation
Dendritic cell: antigen presentation
Basophil: helminth infections
Lymphoid lineage
Similar size to RBC
Little cytoplasm with few granules
- B cells (adaptive)
- T cells (adaptive)
- NK cells (innate)
Lymphoid lineage function
B cells: make antibody, antigen presentation
T cells
- CD4 help other components of immunity
- CD8 kill infected cells
NK cells: direct lysis of infected cells and antibody dependent cellular cytotoxicity
Cytokines
Small proteins released by cells that have an effect on another cell
Important for communication between cells of the immune system and between immune system cells and other cells and tissues
Chemokines
Different structure, receptor and nomenclature
Main role is temporal and spatial organisation of cells and tissues
Antigen receptors
The receptor that cells use to recognise antigen is a key concept in immunology, and forms the basis of separating two immunological arms: innate and adaptive
Key features of innate antigen receptors
Do not recognise antigen specificity
- pattern recognition receptors (PRRs)
- recognise pathogen associated molecular patterns (PAMPs)
Genome encoded
Not clonally distributed
Manose binding ligand
BML binds with high affinity to mannose and fructose residues with correct spacing
Mannose and fructose residues that have different spacing are not bound by MBL
Classic features of innate immune receptors
Work quickly- first line of defence
Adaptive immunity takes more time to be activated
Unable to learn as germline encoded and therefore cannot change- therefore no memory
Key features of adaptive antigen receptors
Recognise antigen specificity
T cell receptor, B cell receptor
Produced by random somatic recombination events between gene segments
Huge receptor diversity
Clonally distributed
Permit specificity and memory in immunity
B cell receptor
May be surface bound or secreted
Recognises intact antigen
T cell receptor
Very similar to B cell receptor
Only a surface receptor on CD4 and CD8 T cells
Recognises processed antigen in the form of linear peptides
Somatic recombination events
T and B cell receptors produced by random recombination events between V and J gene segments
Produces huge receptor diversity despite a small number of genes
Most useful receptors selected after birth upon exposure to pathogens
