Immune System – Study Guide

immune system
internal defense system consisting of organic molecules and cells that protect the body by altering physiology and destroying pathogens; innate and adaptive divisions

pathogen
foreign, disease-causing agent; may be viral, bacterial, protozoan, parasitic, toxins, etc

antigen
any macromolecule or portion that is recognized by the immune system as being foreign and pathogenic; triggers immune response; often specific to strains of pathogenic virus, bacterium…etc

immunity
being “safe” from a particular pathogen; responds to and removes a pathogen before disease

innate immune system
division of the immune system; provides immediate and generalized defense against pathogens
all animals possess some type of this system – includes body covering, phagocytosis, inflammation, antimicrobial peptides, complement system

adaptive immune system
division of the immune system; provides highly specific defense adjacent particular macromolecules present in particular pathogens referred to as antigens
sometimes called acquired immune system – new immunities gained over time; only possessed by vertebrates

phagocytosis
process of immune cell engulfing any enzymatically breaking down another cell or foreign macromolecule

phagocyte
general term for immune cells that phagocytoses pathogens
macrophages and neutrophils – primary vertebrate phagocytes

cytotoxic cell
cell that destroys target cells with cytotoxic peptides (molecules that cause cells to lyse – digest itself)
includes natural killer cells and T cells

inflammation
physiological change in tissues; inhibits growth and division of some pathogens, recruits immune cells, promotes immune cell activity
local cellular response to pathogens – may become systematic (fever)

inflammation
secretion of cytokines that attract and activate phagocytes – causes vasodilation of surrounding arterioles increasing blood flow and temp
raised temperature; redness; edema (swelling); pain

PRR
pattern recognition receptors; plasma membrane receptors found on immune cells; recognize pathogen-associated molecular patterns
immune cells become active and produce inflammation in surrounding tissue by secreting cytokines and/or start phagocytosing recognized pathogens

PAMPs
pathogen-associated molecular patterns; macromolecules or portions that are specific to large groups of pathogens; allow immune cells to recognize forgetn agents
antigens are highly specific, these are generic

self-antigen
plasma membrane molecule that identifies a cell as belonging to the body, often glycoproteins; encoded by MHC genes are self-antigens

antimicrobial peptides
diverse set of short polypeptides produced by immune cells that attack and inactivate or kill pathogens
generic defenses used by all domains of life

complement
plasma proteins that complement the actions of the innate and adaptive immune system divisions;
PAMPs, antigens, antigen-antibody activated
once activated: lyse cells; coat pathogens; attract leukocytes; stimulate inflammation

innate immune response cells
involved in both immune responses if T cells, B cells, or antibodies are mentioned

epithelial cells
of innate immune system; if infected, can form antigen-MHC I complexes to act as APCs or be flagged for destruction by ctotoxic cells
release cytokines to promote inflammation and chemotaxis; release antimicrobial peptides

mast cells
of innate immune system; non-circulating basophils; use TL receptors and Ige antibodies to detect PAMPs and antigens
activation releases histamines that produce local inflammation

neutrophils
of innate immune system; have TL receptors to detect PAMPs and phagocytose pathogens; release cytokines for inflammation and chemotaxis

macrophages
of innate immune system; agranular leukocytes; one kind of mature monocytes; similar to neutrophils response to pathogens; wandering phagocytes

dendritic cells
of innate immune system; agranular leukocutes; one kind of mature monocytes; do not wander, stay put until encounter a pathogen and become and APC

natural killer NK cells
of innate immune system; cytotoxic lymphocytes; have receptors that recognize altered cells; have antibody receptors to detect antibody marked pathogens or infected cells

cytokines
hormones of immune system; produced by immune cells to communicate with or activate other immune cells; used to regulate body physiology
used by non-immune cells to communicate with immune cells;

interferons
of cytokines; produced by macrophages, primarily used to stimulate phagocytosis and cytotoxic destruction of body cells
type I inhibit viral replication in infected cells, activate NK cells
type II stimulate macrophages to phagocytose tumor cels and infected cells

interleukins
of cytokines; produced by macrophages and lymphocytes; facilitate interactions between leukocytes
stimulates inflammation and fever

tumor necrosis factor
of cytokines; produced by macrophages and T cells to increase inflammation; can produce fever if concentration is high

chemokines
of cytokines; primarily cause chemotaxis; attract leukocytes to infected tissues

adaptive immune response cells
T and B lymphocytes are primary cells responsible for cell-mediated and antibody-mediated response; adapts its defenses to pathogens over time through a process of selection and retention of most successful defenses

APC
of adaptive immune system; antigen-presenting cells; any cell that has phagocytosed or become infected with pathogen, incorporating a portion of pathogen with its self-antigen; macrophages and dendritic are “professional”

T cells
of adaptive immune system; lymphocytes originating from stem cells in bone marrow, divide and mature in thymus
detect antigen-self-antigen complexes presented by APCs using receptors TCR; migrate to lymph nodes and wait for APCs

TCR
of adaptive immune system; T cell receptors; have highly variable domain; variation allows for TCR-antigen specificity

helper T cells
of adaptive immune system; have surface protein CD4; activated by TCR binding with antigen-self-antigen complex
activated – expand clonally and can further activate T and B cells; highest affinity TCRs will be favored with interleukin survival signals to become memory T cells

cytotoxic T cells
of adaptive immune system; have surface protein CD8; activated by TCR binding with antigen-self-antigen complex
activated – expand clonally and migrate to site of infection; require leukins from helper T cells to start destroying infected cells; highest affinity TCRs will be favored

memory T cells
of adaptive immune system; T cells with effective TCRs; receive interleukin survival signals develop;
quick to activate – become cytotoxic T cells upon secondary infection by a pathogen with the recognized antigen

B cells
of adaptive immune system; lymphocytes originated, divided and matured in bone marrow; migrate to lymph nodes
detect antigen-self-antigen complexes presented by APCs using BCR; require interleukins from activated helper T cells in order to mature to plasma cells

antibody
of adaptive immune system; four peptide macromolecule; consists of 2 heavy chains and 2 light chains shaped like a Y; bind to assigns disabling pathogens or marking pathogens for phagocytosis or cytotoxic death

V(D)J recombination
of antibody; gene for heavy chain has section called variable domain with 3 regions involved in recombination to create antibody diversity

variable domain point mutation
of antibody; activated B cells clonally expand, each daughter clone produces a slightly different antibody with different affinity for the antigen

IgA
of antibody; isotype found in mucosa and breast milk

IgD
of antibody; isotype found as a BCR

IgE
of antibody; isotype produces in response to parasites and allergens; can attach to mast cells to use as allergen receptors

IgG
of antibody; isotype produced during secondary infection by antigen producing pathogen; can pass from mother to fetus through placenta and protect fetus during gestation

IgM
of antibody; isotype found as BCR and released into blood during primary pathogen infection

isotype switching
of antibody; plasma cell producing a certain antibody can be induced to switch production from one to another; has same variable region but different constant region
changes function without changing antigen specificity

active immunity
immunity to a pathogen with a certain antigen due to possession of memory T and B cells that produce antigen-specific TCRs and antibodies; last years

passive immunity
immunity to a pathogen with a certain antigen due to acquired antibodies