Immune System Flashcards
Actions of activated macrophages
- Phagocytizes the invader through endocytosis
- Digests the invader using enzymes
- Presents little pieces of the invader (mostly peptides) to other cells using MHC
-also release cytokines, chemical substances that stimulate inflammation and recruit additional immune cells to the area
MHC-I
All nucleated cells and presents endogenous antigens
MHC-II
In antigen-presenting cells and presents exogenous antigens
Professional antigen-presenting cells
Macrophages, dendritic cells in the skin, some B-cells, and certain activated epithelial cells
Pattern recognition receptors (PRR)
special receptors of macrophages and dendritic cells (ex. toll-like receptors (TLR))
- able to recognize the category of the invader (bacterium, virus, fungus, or parasite)
- allows for the production of appropriate cytokines to recruit the right type of immune cells
Natural killer cells
type of nonspecific lymphocyte able to detect the downregulation of MHC and induce apoptosis in virally infected cells
Neutrophils
- most populous
- very short-lived-phagocytic
- target bacteria
- follow bacteria using chemotaxis
- can detect bacteria that have been opsonized
- responsible for formation of pus during an infection
Opsonization
Cells that are marked with an antibody from a B-cell
Eosinophils
- contain bright red-orange granules
- primarily involved in allergic reactions & parasitic infections
- release large amounts of histamine
Histamine
Causes vasodilation and increased leakiness of the blood vessels, allowing additional immune cells especially macrophages and neutrophils) to move out of the bloodstream and into the tissue
Basophils
- contain large purple granules
- involved allergic responses
- least populous leukocyte in the bloodstream under normal conditions
- closely related to basophils mast cells
- release large amounts of histamine in response to allergens, leading to
Mast cells
- closely related to basophils, but have smaller granules and exist in the tissues, mucosa, and epithelium
- release large amounts of histamine in response to allergens, leading to inflammatory responses
Three main effects circulating antibodies can have on a pathogen
- Once bound to a specific antigen, antibodies may attract other leukocytes to phagocytize those antigens immediately (opsonization)
- May cause pathogens to clump together (agglutinate), forming large insoluble complexes that can be phagocytized
- Can block the ability of a pathogen to invade tissues, essentially neutralizing it
Action of interferons
- prevent viral replication and dispersion
- cause nearby cells to decrease production of both viral and cellular proteins
- decrease the permeability of nearby cells, making it harder for a virus to infect them
- upregulate MHC class I and class I molecules, resulting in increased antigen presentation an better detection of the infected cells by the immune system
Isotype switching
The ability of cells to change which isotype of antibody they produce when stimulated by specific cytokines
