defence cells Flashcards
what is microbial dysbiosis?
dental plaque build up
does removal of plaque always resolute periodontitis?
no
what happens to the immune and inflammatory cells in the periodontium during progression of periodontitis?
increase
what are examples of innate immune cells?
monocytes/macrophages, mast cells, neutrophils, eosinophils/basophils - all come from stem cells in the bone marrow
describe monocytes
circulate blood as precursors, migrate into tissues and differentiate into mactophages
describe macrophages
- early responders to infection/tissue damage
- long lived with multiple functions
- phacocytose (digest microbial cells) and present antigens
- major role in orcestrating immune response
describe mast cells
- Granulocytes (granules released have antimicrobial effect)
- 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
- produce histamine
what does a loss of mast cells lead to?
enhanced disease progression
describe neutrophils
- Phagocytic granulocytes- granules contain degradative enzymes and antimicrobial substances
- Most numerous/important cells in innate immune responses
- Circulate in blood and move into tissue when required
- Contain numerous granules (intracellular vesicles)
- release neutrophil extracellular traps- catch microbes to prevent infection
describe 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 are the two categories of defence cells?
myeloid and lymphoid
what are examples of myeloid cells?
Neutrophils
Macrophages
Mast cells
Eosinophils
Basophils
what are examples of innate and adaptive cells?
- dendritic cells
- natural killer cells
- innate lymphoid cells
describe dendritic cells
- Derived from myeloid and lymphoid lineage
- Several types of DCs (e.g., Langerhans cells)
- Main role is antigen presentation, and to orchestrate adaptive immune response
- Move from tissues to lymph nodes passing on - information
- Activate T cell and B cells
what do the spindle like structures off of dendritic cells do?
detect antigens
how does memory generation from dendritic cells work?
- 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
describe natural killer cells- dont worry too much
- Considered part of innate immunity (unlike myeloid cells)
- Large cells with granules
- Recognize and kill abnormal cells/tumours/viral infected cells
- Important for ‘holding back’ virus infections until adaptive immunity kicks in
- Have a cytotoxic activity – can attach and degrade abnormal cells through release of lytic granules
describe innate lymphoid cells
- 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
what are examples of adaptive immune cells?
- T cells
- B cells
describe T cells
- T cells although they are derived from the bone marrow they mature in the Thymus (hence the ‘T’)
- Circulate in the blood and the lymph and are found in large numbers in lymphoid organs
- T cells give rise to cellular immunity
- Evolved to protect against intracellular microbes and to help B cells responses
- Recognize peptides presented by APCs through the T Cell Receptor (TCR)
- Diversity in TCR (can respond to numerous antigens): T cell repertoire
- Checkpoints in place however to ensure T cells only respond to foreign pathogens and not ‘self peptides’
what are the three main types of T cells?
- T helper cells (CD4+) function to help support other immune cells to fight threats
- 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
- 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 signals of CD4+ T cells?
1’ MHC-TCR interaction
2’ co-stimulatory molecules interactions (CD80/CD86 and CD40 on DC —- CD40L and CD28 on T cell)
3’ signal dictates what T helper cell the naïve cell becomes
describe B cells
- 2 main types- plasma and memory B cells
- Communicate with T cells
- Have a specific B cell receptor for antigens
- B cells produce antibodies
- Clonal expansion leads to generation of two subsets
- Plasma cells are great big antibody factories
- Memory B cells are important to mount a quicker antibody response to any subsequent infections
