Primers in Immunology: Major Concepts of Host Defense Flashcards
Immune system appropriate response examples
Destruction of cancer cells
Destruction of infectious organisms
Immune system inappropriate response examples
Allergy and hypersensitivity
Transplant rejection
Immunodeficiency
Autoimmune
4 Pathogenic organisms
Virus
Bacterial
Protozoa
Worms
Fixed elements of immune system
Lymphoid organs
- bone marrow (primary)
- thymus (primary)
- spleen and lymph nodes
- mucosal immune tissue
Mobile elements of immune system
cells derived from the bone marrow
soluble (humoral) components
Innate (natural) responses
occur to the same extent every time infectious agent is encountered
- rapid response - minutes to hours
- relatively nonspecific - recognizes pathogens but doesn’t distinguish
- no memory
Acquired (adaptive) responses
improve on repeated exposure to a given infection
- slow response - days to weeks
- specific - tailored for particular pathogen (Ag)
- has memory - response is greater upon repeated exposure
Non-phagocytic cells
Only release inflammatory mediators
- Basophils
- mast cells
- eosinophils
- natural killer (NK) cells
Phagocytic cells
Immune cells capable of phagocytosis Also release inflammatory mediators -neutrophils -monocytes -macrophages
Neutrophils
the most abundant circulating white blood cells capable of phagocytizing and digesting microbes
Monocytes
circulating white blood cells which are precursor cells for tissue macrophages
Macrophages
tissue residing phagocytic cells derived from monocytes. Infection-activated macrophages phagocytize and kill pathogens and secrete inflammatory mediators
Basophils
blood circulating granulocytes which may contribute to immediate hypersensitivity runs (allergy)
Mast cells
tissue residing cells involved in allergic reactions. Contain numerous granules filled with inflammatory mediators which being released trigger the immediate hypersensitivity rxns
Eosinophils
defense against extracellular parasites
-contribute to allergic diseases (late phase rxns)
NK Cells
subset of lymphocytes involved in innate responses
-recognize and kill abnormal cells such virus-infected cells or tumor cells
Complement
a system of serum and cell surface proteins which upon activation generate an important defense mechanism. Activation of Complement results in a cascade of enzymatic reactions that produce inflammatory mediators and opsonins
Acute-phase proteins
plasma proteins which concentration is increased in response to inflammation
Ex. C-reactive protein
Cytokines
A large family of low-molecular weight soluble proteins involved in regulating cellular activity
Chemokines
chemotactin cytokines that regulate the transit of leukocytes from blood into tissues
Antigen (Ag)
any molecule that provokes an immune response
Acquired immunity
involves proliferation of antigen-specific B and T cells
-occurs when the surface receptors of these cells bind to antigens
Antibody (Ab)
a type of protein molecule that is also called immunoglobulin
-produced by B cells and exhibits a high degree of specificity to Ag
T cell Receptor (TCR)
an antigen receptor on cell membrane of T lymphocytes that recognize foreign peptides presented by Ag-presenting cells
Cells involved in acquired immune responses
APC
B cells
T cells
Antigen presenting cells
(APC)
display the antigen to lymphocytes and collaborate with them in the response to the antigen
B cells
secrete immunoglobulins, the antigen-specific antibodies responsible for eliminating extracellular microorganisms
T cells
the cell type that mediates cell-mediated immune response of adaptive immunity. T cells are matured in the thymus and circulate in blood. Once activated by specific antigen, T cells are recruited to a peripheral site
2 Cell types central to adaptive immune response
T and B lymphocytes
Phase I immune system
0-4 hours
Non-induced innate/non-specific response
-preformed defenses (skin barrier, pH, saliva proteases)
Phase II immune system
4-96 hours
Induced innate/broadly specific response
-phagocytosis, complement activation, other inflammatory mechanism, cytokine secretion
Phase III Immune system
> 96 hours
Induced adaptive/highly specific response
-B cells (Ab), helper T cells, cytolytic T cells
Developed germ theory
Koch
Practice of vaccination and variolization
Jenner
Gram positive bacteria
Have large layer of peptidoglycan
Gram negative bacteria
Single layer of peptidoglycan
LPS
Cell-mediated defense deals with _______ pathogens
Intracellular
Antibody mediated defense deals with ______ pathogens
Extracellular
Viruses
Immune response is dependent on location
At some stage, will express viral antigens that will be recognized and destroyed
