Introduction to immunity and pathology Flashcards
Immunology definition
the study of the immune system
Pathology definition
the study of the causes/effects of disease
Why is immunology and pathology important?
to provide the correct diagnosis, treatment, referrals and patient education/advice
Aetiology definition
causes of a disease or condition (pathology)
Possible aetiology of a disease/condition
genetic (e.g hereditary) and/or environmental (e.g. diet, alcohol, smoking)
Pathogenesis definition
Progressive changes as disease develops, involving morphological cellular changes (macro/microscopic)
Sequalae definition
The next steps which often involves intervention.
Examples of two common oral pathologies
oral cancer (usually oral squamous cell carcinoma), periodontitis
What is the aetiology of oral cancer?
excessive alcohol/tobacco consumption increases susceptibility (environmental), can also be genetic
What is the pathogenesis of oral cancer?
processes of hyperplasia, dysplasia, neoplasia
What is the sequalae for oral cancer?
Radiotherapy, surgery, patient advice
What is the aetiology for periodontitis?
Bacteria origin (plaque)
What is the pathogenesis of periodontitis?
inflammation in gingival tissues, bone resorption
What is the sequalae in periodontitis?
physical debridement of plaque, removal of infected tissue, patient advice
What systemic diseases is periodontitis linked to?
Diabetes, rheumatoid arthritis, respiratory disease, stroke, Alzheimer’s disease
What is the aetiology of rheumatoid arthritis?
environmental and/or genetic factors, other diseases (e.g. periodontitis)
What is the pathogenesis of rheumatoid arthritis?
joint inflammation, increased osteoclast activity, circulating ACPA (antibodies)
What is the sequelae of rheumatoid arthritis?
NSAIDs (medicines that relieve pain and inflammation), steroids, treatment of other diseases (e.g. periodontitis treatment to ease RA)
Examples of cells that make up the immune system
leukocytes, lymphocytes, epithelial cells, endothelial cells
How are the organs and cells of the immune system connected?
Lymphatic system (allows immune cells - lymphocytes and leucocytes - to circulate)
What makes up the lymphatic system?
Lymph, lymphatic vessels, lymphoid organs, lymphoid tissues, immune cells
What are the primary sites of the lymphatic system?
The sites where immune cells are created and mature
What are the secondary sites of the lymphatic system?
The sites where immune cells are stored and proliferate
What is lymph?
A clear, colourless fluid that circulates through the lymphatic system
Where does lymph originate?
From excess interstitial fluid that surrounds the body’s cells
What is lymph made up of?
> 90% water, proteins (antibodies), immune cells, waste products (CO2 and urea)
What are the lymphoid organs?
Lymphatic vessels, lymph nodes, thymus, bone marrow, spleen, specialised tissues (e.g. tonsils, adenoid)
Name the primary lymphoid organs
thymus and bone marrow
Name the secondary lymphoid organs
lymph nodes, spleen, specialised lymphoid tissues (e.g. tonsils, adenoid)
Location of thymus
mediastinum (central in chest, posterior to lungs)
How does thymus size differ from a newborn to an adult?
Thymus decreases in size
Function of thymus
Site of T cell maturation and education (T for thymus)
What colour bone marrow produces haemopoietic stem cells?
red bone marrow
Function of haemopoietic stem cells produced in the red marrow
Haemopoietic stem cells differentiate into different types of immune cells
Function of spleen
Secondary lymphoid organ involved in blood filtration system
Function of lymph nodes
Secondary lymphoid organ involved in lymph filtration system
Function of specialised lymphoid tissues
Immunological barriers, mucosal surfaces (e.g. tonsils, adenoids, parts of gut)
What are the two branches of the immune system?
innate and adaptive immunity
What is innate immunity?
the first line of non-specific defence
What is adaptive immunity?
specific and acquired defence involving B and T cells
Which branch of the immune system is involved in creating immunological memory?
Adaptive immunity (specific receptors on B and T cells)
What is humoral?
‘Liquid/fluid’ - proteins produced by the cellular components
What are the innate immune cells?
leukocytes - e.g. monocytes/macrophages, mast cells, neutrophils, NK cells, eosinophils, basophils
What are the adaptive immunity cells?
Lymphocytes - B and T cells
Examples of non-professional immune cells
endothelial/epithelial cells (not from bone marrow stem cells)
Which type of immunity is present from birth?
innate immunity
Which type of immunity is active in the first 1-4 days of exposure to the pathogen?
innate immunity
Which cells contribute to innate immunity, alongside the leukocytes?
non-professional immune cells - epithelial cells, endothelial cells, fibro blasts (e.g. mucous membrane)
Does innate immunity provide lasting protection?
No - no memory
Which type of immunity do vaccines utilise?
Adapted immunity
At which day after pathogen exposure is adaptive immunity active?
day 4-10
What are the two types of responses that make up adaptive immunity?
Cell-mediated and humoral (antibody) responses
Which cells are involved in cell-mediated immunity?
T cells drive cell-mediated immunity with the activation of macrophages, NK cells, epithelial cells
Which cells drive humoral immunity?
B cells (produce antibodies)
What cells are defence cells?
Professional (innate/leucocytes and adaptive/lymphocytes) and non-professional (epithelial, endothelial, fibroblasts) immune cells
Function of macrophages
phagocytose and present antigen - multiple functions (M1 and M2 macrophages)
Difference between macrophages and monocytes?
Macrophages migrate and differentiate into tissues whereas monocytes circulate in blood.
Which defence cells are granulocytes?
Mast cells, neutrophils, basophils, eosinophils, NK cells
What are mast cells?
Granulocytes that respond to inflammation and protect against pathogens by degranulation (histamine). They migrate from blood and differentiate in tissues.
What is histamine?
A type of chemical mediator found in granules
Which defence cells are involved in allergies?
mast cells, eosinophils, basophils
What are neutrophils?
phagocytic granulocytes that are the most numerous and important cells in innate immune response. Circulate in blood and move into tissue when required.
What process do neutrophils undergo?
NETosis via degranulation
What is NETosis?
the production of neutrophil extracellular traps that encapsulate pathogens
What are basophils and eosinophils?
granulocytes that undergo degranulation and are both involved in allergy. Have a similar structure to neutrophils and a similar function to mast cells.
Which defence cell plays a major role in anti-parasitic immunity?
eosinophils
What are NK cells?
Natural killer cells are large granulocytes that have long cellular projections (detection). Important in killing host cells.
Which host cells would be destroyed by NK cells?
Cancerous cells, viral infected cells, microorganisms
Which defence cell bridges innate and adaptive immunity?
Dendritic cells (APC)
Function of dendritic cells
phagocytosis and antigen presentation. Also move from tissues to lymph nodes to activate B and T cells.
What is the name of the type of dendritic cell found in the skin?
Langerhans cells
Where do T cells mature?
Thymus
Location of T cells
circulate in the lymph and are stored in lymph nodes
Which defence cell drives cellular immunity (branch of adaptive immunity)?
T cells
Function of T cells
recognise antigens (peptides). there are lots of subsets of T cells that have different functions.
Where do B cells mature?
Bone marrow (red)
Where are B cells located?
Lymph and lymph nodes
Which defence cells drive humoral immunity?
B cells
Function of B cells
produce antibodies (drive humoral immunity), also capable of antigen presentation for T cell activation
How many subsets of B cells are there?
2 subsets
Function of non-professional immune cells?
Epithelial, endothelial cells and fibroblasts play a role in inflammatory (immune) responses