Developing And Maintaining Adaptive Immunity Flashcards
Antigen specificity
Every cell has a unique receptor which binds to a specific antigen
Naive cells
Cells which have never been activated
Effector cells
When cells become activated
Memory cells
Once the cells have been activated
B cells
Antibody producing cells - once activated become Plasma cells
Plasma cells
Activated B cells
Produce antibodies which bind to a specific antigen
Antibodies
Are y-shaped and soluble, they circulate in the blood and bodily fluids, bind to pathogens and either… kill them, mark them for killing or prevent them from spreading
CD4+ helper T cells
Organise immune responses -> produce different cytokines - can differentiate into different cell types
CD8+ cytotoxic T lymphocyte
Kills infected/mutated cells by giving them a signal to die via apoptosis
Clonal selection
T/B cells express receptors of random specificity that only recognise one antigen -? Specific T/B cell binds pathogen causing proliferation -> T/B cell expands population, immune response kills pathogen -> daughter cells produced express identical receptors to the parent -> T/B cell pool now contains increased precursor frequency of pathogen-specific cells
Hematopoietic stem cells
What B and T cells arise from
BcR
B-cell receptor
TCR
T cell receptor
Variable, diversity and joining gene segments
Encode for variable regions in BcRs and TcRs
Somatic recombination
Random pairing of one Variable, one joining and one diversity region
Junctional diversity
Extra/fewer nucleotides at VDJ junctions
Combinatorial diversity
Different alpha/beta combinations, different VDJ combinations, Different heavy/light chain combinations
B cell receptor and antibodies
Recognise soluble antigens in their normal form
T cell receptor interactions with antigens
TcRs cannot recognise antigens in their normal form so must have antigen presented to it on Major Histocompatibility Complex (MHC) molecules on another cells
Antigens must be broken down into peptides then loaded onto MHC molecules and presented on the surface of the cell
Class 1 MHC
On all nucleated cells apart from neurones
Presents only endogenous antigens (proteins from within the cell)
Antigen bound only by CD8+ cytotoxic cells
If antigen presented is non self then cell is killed by CD8+
Class 2 MHC
Only on antigen presenting cells - e.g. dendritic cells
Presents exogenous antigens (proteins outside the cell)
More associated with CD4+ T helper cells
Polymorphism
Multiple variants of a gene within the human population
Cause of diversity in MHC
Co-expression
Alleles inherited from mother and father
Results in diversity in MHC
Polygyny
Multiple independent genes for each MHC type
Cause of diversity in MHC
