adaptive immunity

acquired specific immunity after an immunizing event such as an infection

product of B and T lymphocytes

lymphocytes undergo selective process that specializes them for reacting to only one specific marker

immunocompetence

the ability of the body to react with countless foreign substances

antigens (markers)

molecules that can be seen and identified by the immune system

is it possible for an antigen to not provoke an immune response?

yes

immunogens

antigens that provoke adaptive immune response

stimulate a response by T and B cells

PAMPs

molecules shared by many types of microbes that stimulate an innate response

shared characteristics of PAMPs and immunogens

they are "parts" of foreign cells (other foreign materials)

they provoke a defensive reaction from the host

specificity

highly specific to the antigen against which the third line of defense is directed

memory

the rapid mobilization of lymphocytes that have been programmed to recall their first engagement with the invader and rush to attack once again

major functions of immune system markers

attachment to nonself or foreign antigens

binding to cell surface receptors that indicates self

receiving the transmitting chemical messages to coordinate the response

aiding in cellular development

clonal deletion

occurs when a T or B cell recognizes a "self" marker, and that clone of cells is deleted

major histocompatibility complex (MHC)

set of genes that code for human cell markers

gives rise to a series of glycoproteins called MHC molecules

found on all cells except red blood cells

class 1 MHC genes

markers appear on all nucleated cells

display unique characteristics of self

allow for recognition of self and the regulation of immune reactions

each human inherits a particular combination of class 1 MHC genes

class 2 MHC genes

code for immune regulatory markers found on macrophages, dendritic cells, and B cells

involved in presenting antigens to T cells during cooperative immune reactions

class 3 MHC genes

encode proteins involved with the complement system

cluster of differentiation

markers important in immunity

found on the membranes of variety of different cells involved in the immune response

close to 400 have been described

tissue macrophages

ingest the pathogens and induce an inflammatory response in the tissue if appropriate

tissue dendritic cells

ingest the antigen and migrate to the nearest lymphoid organ

process and present antigen to T lymphocytes

antigen-presenting cells

dendritic cells

macrophages

B cells

clone

proliferation of a particular lymphocyte

genetically identical cells, some of which are memory cells

three main functional types of T cells

helper T cells

regulatory T cells

cytotoxic T cells

helper T cells

activate macrophages, assist B-cell processes, and help activate cytotoxic T cells

regulatory T cells

control the T-cell response by secreting anti-inflammatory cytokines or preventing proliferation

cytotoxic T cells

lead to the destruction of infected host cells and other "foreign" cells

gamma-delta T cells can be activated quickly by

PAMPs and specific antigens

a B cell that is activated by an antigen divides into

plasma cells

each plasma cell has the same

reactive profile

innate response activating B cells

alert many components of the immune system to get active because a threat is on the way in a nonspecific way

CD3 markers

surround the T-cell receptor and assist in binding

CD4

found in helper T cells and binds to MHC class 2 molecules

CD8

found on cytotoxic T cells and binds MHC class 1 molecules

B cells site of maturation

bone marrow

T cell site of maturation

thymus

B cells specific surface markers

immunoglobulin as receptors and distinct CD molecules

T cells specific surface markers

T-cell receptor and distinct CD molecules

B cells concentration in blood

low numbers

T cells concentration in blood

high numbers

B cells receptors for antigen

immunoglobulin

T cells receptors for antigen

T-cell receptor

B cells location in lymphoid organs

cortex (in follicles)

T cells location in lymphoid organs

paracortical sites (interior to the follicles)

B cells result of antigenic stimulation

plasma cells and memory cells

T cells result of antigenic stimulation

several types of activated T cells and memory cells

B cells general functions

production of antibodies to inactivate, neutralize, and target antigens

T cells general functions

cells function in helping other immune cells, suppressing killing abnormal cells; hypersensitivity; and synthesize cytokines

immunoglobulin (Ig)

two heavy chains, two light chains

one light chain is bonded to one heavy chain

two heavy chains are bonded to each other with disulfide bonds

creates a symmetrical, Y-shaped arrangmeent

antigen-binding sites

pockets at the ends of the forks formed by the light and heavy chains

can be highly variable in shape to fit a wide range of antigens

variable regions

found in antigen-binding sites

amino acid position is highly varied from one clone of B lymphocytes to another as the result of genetic reassortment

constant regions

amino acids content does not vary greatly

T cell receptors

formed by genetic modification

has variable and constant regions

inserted into the membrane

has antigen-binding site formed from two parallel polypeptide chains

immune tolerance

tolerance to self

removal of any potentially harmful clones through clonal deletion

some autoimmune diseases are thought to be caused by the loss of immune tolerance, the survival of "forbidden clones" or failure of other systems

antigen

a substance that provokes an immune response in specific lymphocytes

immunogen

an antigen that has been responded to by the immune system

characteristics of antigens

must be perceived as foreign

whole microbes or parts

cells or substances that arise from other humans, animals, plants, and various molecules

molecules such as proteins or protein-containing compounds are more immunogenic than repetitious polymers composed of a single unit

antigens that provoke a strong response are considered

good

good antigens are so named because of

their chemical composition

their context, meaning what types of cytokines are present

their size

epitope

a portion of the antigen molecule recognized and responded to by a lymphocyte

the primary signal that a molecule is foreign

haptens

consist only of a determinant group

too small by themselves to elicit an immune response

if linked to a carrier group, the combined molecule develops immunogenicity

alloantigens

proteins and other molecules of one person which are antigenic to another

cell surface markers that occur in some members of the same species but not in others

the basis for an individual's blood group and major histocompatibility profile

responsible for incompatibilities that occur in blood transfusion or organ grafting

superantigens

bacterial toxins

potent stimuli for T cells

antigens' routes of entry

respiratory mucosa

gastrointestinal mucosa

mucous membranes

the skin

across placenta

intravenously

when antigens are introduced intravenously

they travel through the bloodstream and end up in the liver, spleen, bone marrow, kidney, and lung

lymph nodes and spleen

important in concentrating the antigens

circulating antigens thoroughly through all area populated by lymphocytes

APCs

macrophages, B cells, dendritic cells

T helper cells

play a central role in regulating immune reactions to antigens

involved in activating macrophages

stimulation of T helper cells

antigen/MHC complex

regulatory T cells

carry CD4 markers

control the inflammatory process

prevent autoimmunity

cytotoxicity

the capacity of certain T cells to kill a specific target cell

cytotoxic T cell (CD8) activation

must recognize a foreign peptide complexed with self MHC-1 presented to it and mount a direct attack on a target cell

perforins

proteins that punch holes in the membranes of target cells

causes ions to leak out of target cells

creates a passageway for granzymes to enter

granzymes

enzymes that attack proteins of target cells

target cells of cytotoxic T cells

virally infected cells

cancer cells

cells from other animals and humans

gamma-delta T cells

distinct from other T cells

have T-cell receptors rearranged to recognize a wide range of antigens

response to certain PAMPs on microorganisms

respond quickly

produce memory cells when they are activated

natural killer cells

lymphocyte related to T cells

lack specificity for antigens

circulate through the spleen, blood, and lungs

hybrid type

share properties of both T cells and NK cells

display T-cell receptors and NK-cell markers

two functionally distinct fragments basic immunoglobulin

antigen-binding fragments

crystallizable fragment

Fab fragment

amino terminal end consists of the variable regions of the heavy and light chains

special region of attachment between the Fab and Fc regions allows swiveling of the Fab fragments

Fc fragment

serves as an anchor

involved in binding to various cells and molecules of the immune system itself

hypervariable region

site on the antibody where the epitope bind

amino acid content is extremely varied

a minimal complementary fir is necessary for the antigen to be held effectively

opsonization

the attachment of antibody to foreign cells and viruses exposes the epitopes to which they are bound to phagocytes

J chain

joins the monomers of IgA and IgM

secretory component

helps IgA move across mucous membranes

titer

the concentration of antibodies in the serum

can be measured over time to determine how the immune system reacts to antigen

latent period

marked by a lack of antibody production

antigen is concentrated in lymphoid tissues

active immunity

immune stimulus

creates a memory that renders the person ready for quick action upon reexposure to the same antigen

requires several days to develop

last for a long time

passive immunity

occurs when an individual receives substances that were produced actively in the body of another human or animal donor

lack of memory for the original antigen

lack of production of new antibodies against that disease

natural immunity

any immunity that is acquired during the normal biological experiences of an individual

it is not obtained through medical intervention

artificial immunity

induced by immunization with vaccines or the administration of immune serum

it is obtained through medical intervention

intravenous immune globulin

extracted from the pooled blood of human donors

IVIGs are processed to concentrate antibodies to increase potency and eliminate potential pathogens

most forms are injected intramuscularly

specific immune globulin

derived from a more defined group of donors who are convalescing in a hyperimmune state after certain infections

contain high titers of specific antibodies obtained from a smaller pool of patients

vaccination

exposing a person to material that is antigenic but not pathogenic

discovery of vaccination was one of the farthest reaching and most important developments in medical science

basic principles

stimulate a primary immune response that primes the immune system for future exposure to a virulent pathogen

if the pathogen later enters the body, the secondary immune response will be immediate, powerful, and sustained

vaccine considerations

antigen selection

effectiveness

ease in administration

safety

cost

live, attenuated cells or viruses

continues to stimulate strong immunity due to the pathogen's ability to replicate in the vaccine recipient

whole killed cell or inactivated virus

contains a wide range of surface markers that can activate the immune responses

adjuvant

a special binding substance added to some vaccines

any compound that enhances immunogenicity and prolongs antigen retention at the injection site

precipitates the antigen and holds it in the tissues so that it will be released gradually

facilitates contact with APCs and lymphocytes

common side effects of vaccine

local reactions at the injection site (soreness)

short-term flu-like symptoms (caused by our immune response)

most common serious side effect vaccine

risk anaphylaxis

for the COVID-19 vaccine, five cases out of a million resulted in anaphylaxis