L1- Introduction Flashcards
What are mast cells?
Cells found in tissues which are important in inflammation and allergy, they release granules containing inflammatory mediators such as histamine.
What are the two arms of the immune system?
Innate= fixed, rapid, non specific
- Involves first line barriers to entry
- Recognition of PAMPS by immune cells causes responses such as lysis, phagocytosis and inflammation.
Adaptive= specific recognition and destruction
Cellular response is T cells
Humoural response is B cells
What are examples of first line barriers to entry?
Cilia in the nasopharynx
Lysosymes in tear glands
Skin
HCL in stomach and duodenum
What cells are involved in the different types of immunity?
Innate: Macrophages, Granular cells (neutrophils,eosinophils,basophils), Dendritic cells
Adaptive: B cells, T cells
Both: Natural killer T cells
How are immune cells generated?
Originate from the haematopoietic stem cell which is multipotent and self renews and is found in bone.
It differentiates into different immune cell types in the bone marrow and terminal differentiation occurs in the blood and tissues.
What is the purpose of stromal cells in the bone marrow?
Stromal cells support the growth and differentiation of haematopoietic stem cells by generating the supporting matrix and producing soluble growth factors for cell differentiation.
What soluble growth factors do stromal cells produce?
Erythropoietin, Granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte CSF.
How is haematopoiesis controlled?
Growth factors drive the expression of certain genes (transcription factors) that in turn control development of certain cell types.
Some cells are removed by the induction of programmed cell death (apoptosis)
What are monocytes?
Found in the circulation as monocytes and mature into macrophages inside tissues. Can also become dendritic cells.
They are the largest leukocyte.
Carry out phagocytosis.
Macrophage- RIOT POLICE
Dendritic cell- TRAFFIC POLICE
What are neutrophils?
Found in the circulation and only enter tissues when instructed during inflammation.
Responsible for phagocytosis and bactericidal killing mechanisms.
Most abundant leukocyte, die quickly.
POLICE OFFICER
What are eosinophils?
Found in the circulation.
Responsible for killing large antibody coated parasites like worms.
Release chemical substances to perforate cell membranes.
FUMIGATOR
What are basophils?
Found in the circulation.
Smallest leukocyte.
Involved in inflammation and allergic reactions by releasing histamine and heparin from granules.
FIREMAN
What are T-lymphocytes?
Recognise specific antigens via TCR’s.
CD4+ are helper T cells that activate specific B cells to produce humoural response.
CD8+ are cytotoxic T cells that kill infected cells by releasing cytotoxins like perforins.
What are B-lymphocytes?
Involved in the humoural immune response and are activated by their cognate Th cells.
Differentiate into plasma (CD138) cells and B memory (CD27) cells.
Recognise specific antigens via BCR.
What are natural killer cells?
Group of innate lymphoid cells that are cytotoxic and destroy foreign/infected cells via release of toxic granules and cytokines.
