immune Flashcards
Cytokines
Molecules that control growth and activity of immune cells e.g interleukin and interferon.
Chemokines
Molecules that stimulate migration of immune cells e.g chemical trails
How are MHC-I antigens processed (Endogenous)
- Antigenic proteins are degraded to peptides in the cytoplasm
- The peptides are then imported to the endoplasmic reticulum
- loading of MHC-I occurs at the ER and then the MHC-I with the antigenic peptide is sent to the surface
What are lymph nodes
Secondary lymphatic organs. Nodes along lymphatic vessels where lymph fluid from blood and tissue is filtered. It is the site of immune responses
TCR Gene rearrangement
The variable part of the TCR is rearranged. This process if completely rearranged and increases the diversity of the T-cell repertoire.
BCR (B cell receptors)
The surface of each B cell contains 100,000 BCR (mainly IgM and IgD).
BCR bind to native antigen, which activates the B cell.
BCR are antibodies that are membrane anchored by transmembrane domains.
antimicrobial peptides
Also called defensins. Found in the dermis of the skin.
Function is to form pores in the microbial cell membrane
Describe the Physical and chemical characteristics of the mucosal membrane.
The mucosal membrane is made up of 1-2 tightly packed live epithelial cells that are constantly being renewed and contain mucous producing goblet cells.
They line parts of the body that lead to the outside and are exposed to air.
The mucociliary escalator uses cilia to move mucous up to the pharynx.
Chemically, the stomach has low pH, gall bladder produces bile, intestines have digestive enzymes, mucous, defensins, lyzozymes (tears, urine)
Neutrophils
Granulocytes in the blood. Circulate the blood and can move into tissue during inflammation.
Neutrophils make up 75% of all leukocytes, are highly phagocytic, and numbers in blood increase during infection.
Mast Cells
Granulocytes in tissue. Line the mucousal surfaces (not found in tissue). They release granules to attract white blood cells during infection.
Monocytes
Low phagocytosis in blood but can move to tissues e.g spleen, liver, where they become macrophages.
Macrophages
In tissues they can be resident (sessile) or move through the tissues (migratory). They have 3 functions, phagocytosis, release of chemical messengers, and antigen presenting to T cells.
Dendritic cells
Phagocytic cells found in low numbers in the blood and all tissues in contact with the environment. They are antigen presenting, and are the most important cell for linking the innate and adaptive immune response.
How are immune cells carried around the body?
Cells are carried in blood and lymph. The cells can leave the blood into the tissues as required.
Fever
Fever/pyrexia is an abnormal increase of body temperature above 37 degrees. It is a resetting of the thermostat (hypothalamus). Pyrogens are released by cells of the immune system, such as cytokine interleukin-1 that is produced by phagocytes, this produces fever. Fever is useful because it enhances the performance of immune cells, and produces unfavourable conditions for pathogens.
Describe the 6 steps of the inflammatory response.
- Tissue resident cells release chemical signals that attract more immune cells to the site of infection
- Leukocytosis: Neutrophils enter the capillary from the bone marrow.
- Margination: Neutrophils cling to the capillary wall.
- chemical signals from tissue resident cells cause the blood vessel to dilate, causing the capillary to become leaky.
- Diapsedis: neutrophils squeeze through the leaky capillary wall.
- Chemotaxis: neutrophils follow the chemical trail towards the site of infection
What activates classical pathway
Complement binding to antibody on pathogen
What activates alternative pathway
Complement bound to pathogen binds to surface/pathogen component.