immune system Flashcards
non-specific resistance
aka natural immunity
immunity that is immediate throughout the body and serves as protection against a wide array of pathogens
present from birth
chemical and mechanical barriers of non-specific resistance
first-line of defense
tears
skin
mucous membranes
second line of defense of non-specific resistance
inflammation
fever
phagocytosis
complement and interferon (protective proteins)
antigen
molecule recognized as foreign by immune system and elicits an immune response
MHC
proteins found on a cell’s surface that distinguish b/w self and non-self
tissue transplant
recipient’s immune system recognize the transplanted tissue as foreign due to diff MHC proteins
leads to rejection and attacking of these cells within the recipient’s body
prevented via immunosuppressive therapy
immunoglobulin
aka antibodies
proteins produced by immune system and respond to foreign invaders
IgA
prevent pathogens from entering the body through mucosal membranes
IgD
present on the surface of B cells and activate them
IgE
associated w/ allergic reactions and parasites
trigger the release of histamines
IgG
most abundant
long-term immunity
opsonization and the neutralization of toxins
IgM
first antibody produced during an immune response
diversity of immunoglobulins
crucial for the immune system to recognize and respond to a wide variety of pathogens
humoral response
maturation of B cells in bone marrow
clonally expands and produces a population of identical cells
some become plasma cells and secrete antibodies
form memory cells
has extracellular targets
cell-mediated immunity
T cells mature in the thymus
cytotoxic, helper, and suppressor T cells
has intracellular targets
cytotoxic T cells
kill antigens by releasing cytotoxic substances
targets cancers, virus-infected cells, intracellular bacteria/parasites, mismatched transfusions, and organ transplants
helper T cells
release cytokines that stimulate the release of other immune cells
suppressor T cells
suppress immune responses that are too excessive in nature via cytokines (IL-10 and TGF-B)
clonal selection
naive lymphocyte’s first encounter w/ an antigen and its selection for further development
secondary immune response
more rapid and heightened immune rxn that occurs upon re-exposure to an antigen
immunological memory
ability of the immune system to remember previous encounters w/ specific antigens and respond efficiently upon re-exposure
memory cells
include B and T cells
remember a specific antigen and produce a faster response upon re-exposure
hapten
small molecules that elicit an immune response and produce antibodies when bounded to larger carrier proteins or macromolecules
ex: drugs, chemicals
causes delayed hypersensitivities
must be presented to T cells along with foreign antigens in order to trigger T cell cloning
adaptive immunity
third-line of defense
attacks particular foreign substances
specific=recognizes and targets specific antigens
systemic=not restricted to initial stie
opsonization
marks pathogen
coating by complement proteins or antibodies
phagocytes
neutrophils
macrophages
phagosome
particles in vesicle
phagocytosis
helper T cells cause release of enzymes of respiratory burst which release cell-killing free radicals, produce oxidizing chemicals, and increase pH and osmolarity of phagolysosome
defensins in neutrophils pierce membrane
NK cells
non-phagocytic large granule lymphocytes
attack cells that lack self cell-surface receptors (MHC class I)
induce apoptosis
enhance inflammatory response
antibody coating target cell (opsinization)
inflammatory response
macrophages and epithelial cells of boundary tissues bear TLRs
trigger release of cytokines that promote inflammation
mediators include kinins, PGs, and complement
dilate arterioles (hyperemia)->causes redness and heat
swelling causes pain
moves foreign material into lymphatic vessels
phagocyte mobilization
leukocytosis
margination
diapedesis
chemotaxis
interferons
family of immune modulating proteins
viral infected cells secrete IFNs to warn neighboring cells
IFN alpha and beta activate NK cells
IFN gamma are secreted by lymphocytes, produce widespread immune mobilizing effects, and activate macrophages
complement system
about 20 blood proteins that circulate in inactive form
each pathway converges on C3 which cleaves into C3a (amplify inflammation->mast cells and basophils release histamine) and C3b (causes opsonization)
kills bacteria via cell lysis when C3b binds to target cells-> insertion of MAC into cell’s membrane->MAC forms and stabilizes hole in membrane-> influx of water
classical pathway
antibodies bind to invading organisms and to complement components
lectin pathway
lectins=produced by innate system to recognize foreign invaders
activates complement when bound to foreign invaders
alternative pathway
activated spontaneously
lack of inhibitors allows process to proceed
fever
leukocytes and macrophages exposed to foreign substances secrete pyrogens
pyrogens act on body’s thermostat in HP, raising body temp.
increases metabolic rate (faster repair)
liver and spleen sequester iron
leukocytosis
release of neutrophils from bone marrow
margination
neutrophils cling to walls of capillaries in inflamed area
chemotaxis
inflammatory chemicals promote positive chemotaxis of neutrophils
lysosomes
fuse w/ phagosomes to form phagolysosomes
macrophages
most numerous at the site of chronic inflammation
in CT and lymphoid organs
self-tolerance
unresponsiveness to our own body cells
neutralization
ability of antibodies to block specific sites on pathogens so they cannot bind to cell receptors
T cell
mediates the body’s cellular immune response
most specific internal defense against disease
helper T cells
promote antibody production by B cells
constant region
structure of antibody that determines its class
immunogenicity
ability to stimulate proliferation of specific lymphocytes
reactivity
ability to react with activated lymphocytes and antibodies released by immunogenic reactions
APCs
do not respond to specific antigens
engulfs antigens
presents fragments of antigens to T cells for recognition
ex: dendritic cells, macrophages, B cells (display antigen fragments bound to MHC class II receptors)
immunocompentance
lymphocyte can recognize one specific antigen by binding to it
positive selection
selects T cells capable of recognizing self MHC proteins (MHC restriction)-> failure results in apoptosis
negative selection
prompts apoptosis of T cells that bind to self antigens displayed by self MHC
ensures self-tolerance
dendritic cells
present in CT and epidermis
steps in lymphocyte development, maturation, and activation
origin
maturation
seeding secondary lymphoid organs and circulation
antigen encounter and activation
proliferation and differentiation
MHC class I
found on all nucleated cells including some APCs like dendritic cells
present antigens to CD8 and cytotoxic T cells
MHC class II
only found on APCs like dendritic cells, macrophages, and B cells
present antigens to CD4 and helper T cells
monoclonal antibodies
laboratory produced molecule that is
designed to mimic the immune system’s ability to fight off pathogens, cancers, autoimmune diseases, etc.
fusion of B cell w/ tumor cell produces a hybridoma which creates large quantities of a single antibody
lymphocyte education
effective immune response against pathogens while preventing harmful immune rxns against self-antigens
alloimmunity
immune response against antigens from individuals of the same species but w/ genetic differences
Ex: mismatched blood transfusion or organ transplants
TLRs
part of innate immune system
1st line of defense
triggers signaling cascade-> immune response, recruitment of other immune cells, activation of adaptive immune system
found on macrophages, dendritic cells, certain types of WBCs, epithelial and endothelial cells
antibody defensive mechanism
neutralization
agglutination
precipitation (antigen-antibody complex formation)
complement fixation
natural active immunity
infection
contact w/ pathogen
natural passive immunity
antibodies transferred from placenta or breastmilk
artificial active immunity
vaccines
artificial passive immunity
injection of antibodies (gamma globulins)
vaccines
provide antigenic determinants that are immunogenic and reactive via dead or attenuated pathogens which spare the symptoms of a primary response
immunodeficiencies
congenital or acquired conditions that impair immune function or production of immune cells or molecules such as complement and antibodies
Ex: SCID and HIV
SCID
genetic defect marked deficient in B and T cells
defective ADA enzyme
treated via bone marrow transplants
HIV
contracted via blood through needles, sex, or mother->fetus
characterized by severe weight loss, night sweats, swollen lymph nodes
more susceptible to opportunistic infections (pneumocystic pneumonia and kaposi’s sacrcoma)
autoimmune disease
immune system loses ability to distinguish self from foreign leading to the production of antibodies and cytotoxic T cells that destroy body tissues
Ex: MS, MG, systemic lupus, Graves disease, RA, glomerulonephritis, erythrematosus, type 1 diabetes
MS
destruction of oligodendritic cells which are responsible for the production of myelin sheath
type 1 DM
destruction of B cells in the pancreas
inhibits insulin production
graves disease
production of antibodies to receptor for TSH
inhibits T3 and T4 production
RA
immune system attacks synovial joints
SLE
targets nucleic acids
immediate hypersensitivities
type 1
acute
due to allergies
can be local (regular allergies) or systemic (anaphalactic shock)
anaphalactic shock
allergen directly enters blood
trigger basophils and mast cells that release histamine throughout body
treated via epinephrine
more severe
can lead to death if not treated
subacute hypersensitivities
caused by IgM and IgG antibodies
cytotoxic rxns and immune complex
cytotoxic rxns
type II
stimulate phagocytosis and cell lysis
Ex: mismatched blood transfusion
immune complex
type III
insoluble antigen-antibody complex
intense inflammation, local cell lysis, cell killing via neutrophils
Ex: SLE, vasculitis, renal damage
delayed hypersensitivities
type IV
cytokine activated macrophages and cytotoxic T cells that cause damage
agents act as haptens-> poison ivy
Ex: TB skin test, contact dermatitis, latex allergy, transplant rejection
granzymes
trigger apoptosis
released by cytotoxic T cells along with perforins when target is recognized
types of humoral immunity
natural active
natural passive
artificial active
artificial passive