Defence Cells Flashcards
What are cells of myeloid (innate) origin?
neutrophils, macrophages, monocytes, eosinophils, basophils, mast cells
What is myeloid?
Having to do with or resembling the bone marrow.
What is lymphoid?
originate from precursor cells in the bone marrow, but they mature in the lymphoid organs, such as the thymus and lymph nodes.
What are cells of myeloid or lymphoid (innate) origin?
dendritic cells,
What are cells of lymphoid (adaptive) origin?
T cells
B cells
Where do nearly all innate and adaptive cells originate from?
bone marrow
5 years after periodontal treatment, what % of patients regress to pre-treatment periodontitis?
45%
What does build up of dental plaque cause?
microbial dysbiosis
Does removal of plaque lead to resolution?
not always
What are the precursors of macrophages?
monocytes
What do monocytes differentiate into?
macrophages
What is the location and characteristics of monocytes/macrophages?
stored in spleen, migrates through blood
early responders to infection or tissue damage
long-lived with multiple functions
phagocytose and present antigen
What type of cell are mast cells?
granulocytes
What are the characteristics of mast cells?
early responders to infection or tissue damage
migrate from blood and differentiate in tissues (blood precursors not well defined)
protect against pathogens (particularly parasitic worms)
best known for role in allergy (release histamine)
What can loss of mast cells in the gingivae lead to?
enhanced PD progression
What type of cells are neutrophils?
granulocytes
What are characteristics of neutrophils?
Phagocytic granulocytes
Most numerous/important cells in innate immune responses
Circulate in blood and move into tissue when required
Contain numerous granules (intracellular vesicles)
Have NETS (neutrophils extracellular traps)
Where are neutrophils found in the oral cavity?
neutrophils are mainly found in the junctional epithelium and in the gingival crevicular fluids
What are characteristics of basophils and eosinophils?
Granulocytes
Less abundant than neutrophils
Contain granules – degradative enzymes and antimicrobials
Eosinophils play a major role in defence against parasites as larger than neutrophils so can ingest larger threats
Both also contribute to allergy (basophils produce histamine)
What is the main aim of dendritic cells?
to orchestrate the adaptive immune response – induce immune memory for adaptive immune cells (B cells/ T cells) to recognise microbial antigens
What is the linage of dendritic cells?
myeloid and lymphoid lineage
What are the functions of dendritic cells?
Degrade pathogens but major function is not clearance but to present antigen (antigen presenting cell [APC]) to T cells (sometimes directly to B cells)
Describe memory generation in DCs
Immature dendritic cells take up and process antigen in the epidermis
Once taken up antigen they migrate to lymph nodes and differentiate along the way
Mature dendritic cells have co-stimulatory activity and can prime naïve T cells
They can also transfer antigen to other dendritic cells resident in the lymph node
What are the characteristics of NK cells?
Considered part of innate immunity (unlike other lymphoid cells)
Large cells with granules
Recognize and kill abnormal cells/tumours/viral infected cells via cytotoxic lytic granules
Important for ‘holding back’ virus infections until adaptive immunity kicks in
What are the characteristics of innate lymphoid cells (ILCs)?
Non-cytotoxic members of NK cell family
Innate immune cell of lymphoid origin (not myeloid)
Link innate and adaptive immune immunity
Three main subsets (ILC1s, ILC2s and ILC3s)
Produce effectors (cytokines) similar to T cell subsets
Where do T cells mature?
thymus
What is the main function of T cells?
cellular immunity
How do T cells recognise peptides?
Recognize peptides presented by APCs through the T Cell Receptor (TCR)
Where are T cells found mostly?
lymphoid organs
T cells can respond to numerous antigens, what is this called?
T cell repertoire
What prevents T cells recognising self peptides?
Checkpoints in place in Thymus (Thymic education) to prevent T cells responding to themselves
What do the 3 T cell types start off as?
All T cells start as a naïve cell and have receptor for very specific proteins (e.g., antigens via DC presentation)
What are the 3 T cell types and what is their function?
T helper cells (CD4+) function to help support other cells by secreting cytokines and activating B cells
Cytotoxic T cells (CD8+) destroy our own cells which have become infected (usually virus-related)
Regulatory T cells (Tregs) regulate or suppress other cells in the immune system
What enzymes do CD8+ cells produce?
perforins
granzymes
What are the subsets of CD4+ cells and what do they do?
TH1 – support macrophage to destroy microbes
TH2 – allergic responses/plasma cell generation (IgE), produce cytokines which recruit and activate mast cells, eosinophils
TH17 – fungi/ extracellular bacteria secrete IL-17, IL-22 cytokines that promotes release of cytokines and chemokines from non professional Immune cells (epithelial cells)
TFH – found predominantly in lymph nodes and important for B cell antibody generation
Tregs – control/dampen the immune response
What do B cells produce?
antibodies
What are the two main types of B cells?
memory and plasma
What leads to a generation of two subsets of B cells?
clonal expansion
What is the function of plasma B cells?
antibody factory
What is the function of memory B cells?
set out a quicker antibody reaction to infections
Apart from the two main types of B cells, what else can B cells do?
B cells also have the potential to take up and present antigen – leading to T cell activation
What are cells of myeloid or lymphoid (innate) cells?
dendritic, NK C, ILCs
How do dendritic cells attach to antigens?
Toll like receptors
What are the 3 signals required for naive T cell determination?
1’ MHC-TCR interaction
2’ co-stimulatory molecules interactions (CD80/CD86 and CD40 on Dendritic cells C —- CD40L and CD28 on T cell)
3’ signal dictates what T helper cell the naïve cell becomes. mediated by cytokine (IL2)
What molecules do B cells also have?
they also have the same co-stimulatory molecules that professional antigen presenting cells have
