microbiology chapter 17

adaptive immunity

defenses that target a specific pathogen

infection or vaccination

how is adaptive immunity acquired?

primary response

first time the immune system encounters a particular foreign substance

secondary response

later interactions with the same foreign substance - faster and more effective dur to “memory”

humoral immunity

refers to the use of antibodies to fight an infection

B lymphocytes (B cells)

immune cells that are created and mature in red bone marrow and are responsible for antibody production

via B cell receptors

how do B cells recognize antigens?

recognize antigens

what do B cell receptors do?

confer with T cells

what do B cells do

plasma cells, memory B cells

what can B cells differentiate into?

plasma cells

antibody producing cells that differentiate from B cells

yes

are B cells able to recognize pathogens on their own?

signals from a T cell

what do B cells need in order to become activated and produce antibodies?

they become activated and produce antibodies

when B cells receive signals from T cells, what happens?

memory B cells

what do B cells differentiate into for rapid antibody production if/when they re-encounter the same antigen in the future

cellular immunity

refers to the activity of T cells

bone marrow, thymus

where are T cells made and mature?

T lymphocytes (T cells)

recognize antigenic peptides that have been processed by phagocytic cells and secrete cytokines to signal other immune cells to clear an infection

recognize antigenic peptides and secrete cytokines

what do T cells do?

antigenic peptides

small pieces of a pathogen

cytotoxic T cells, aka CTLs

directly kill infected cells, have direct cytotoxic effects on infected cells (or cancer cells)

T helper cells

provide “help” to other immune cells by cytokine signaling, coordinate the B cell antibody release

CD4+

T helper cells (TH) = ???

CD8+

Cytotoxic T lymphocytes (CTL) = ???

antigen and MHC class 1, signal to CTL

what does a host cell that has been infected put on their surface to signal that they’ve been infected? who do they signal to?

perforin and granzyme, together induces apoptosis of infected cell

what does a CTL release? what does it do?

perforin

pokes holes in the membrane

granzymes

induce cells death in coordination with perforin

apoptosis

programmed cell death

antigen

substances that trigger the production on antibodies

epitope

the part of an antigen molecule to which an antibody attaches itself

key, antibody’s lock

epitopes are the (___) on an antigen that fit into a (___)?

macrophages

develops from monocytes, large phagocytic cell, presents antigen to T cells

dendritic cells

engulf and degrade microbe, display antigen on their surfaces, responsible for initiation of the adaptive immune response, surveillance cells

B cells

recognize extracellular antigen and present to T cells

immunoglobulins (Ig)

antibodies that are globular proteins

four protein chains that form a Y shape

antibody structure

variable (v) region

are at the ends of the arms; this is where the antibody binds to an epitope

variable (v) region

where does the antibody bind to an epitope?

IgG, IgM, IgA, IgD, IgE

what are the 5 classes of immunoglobulins (Ig)

IgM

main function: neutralize and clear pathogens and initiate inflammation

IgM

First kind of antibody secreted by the adaptive immune system during an infection, is short lived (5-10 days), presence indicates an active ongoing infection

IgA

Main function: prevent microbial attachment to mucous membranes

IgA

common in mucous membrane

IgE

main function: binding of antigen causes the release of histamines followed by lysis of parasitic worms

IgG

main function: enhance phagocytosis; neutralize toxins and viruses

IgG

only class of antibodies that can cross the placenta and protect the fetus

IgG

most common antibody

yes

can IgG antibodies persist for years?

no because it persists for years after an infection has been resolved

can IgG antibodies be used to prove active infection?

monomer

what is the shape of IgG?

monomer

what is the shape of IgD?

monomer

what is the shape of IgE?

dimer

what is the shape of IgA?

pentamer

what is the shape of IgM?

80%

what is the total serum antibody of IgG?

6%

what is the total serum antibody of IgM?

13%

what is the total serum antibody of IgA?

0.02%

what is the total serum antibody of IgD?

0.002%

what is the total serum antibody of IgE?

IgG

what is the only antibody found in placental transfer?

half-life

the time required for the serum concentration to decrease by 50%

23 days, 5 days, 6 days, 3 days, 2 days

what is the half life of the IgG, IgM, IgA, IgD, IgE in order?

T dependent antigen

antigen that requires a Th cell to produce antibodies

T independent antigens

stimulate the B cell without the help of T cells

provoke a weak immune response, usually producing IgM

No memory cells generated

memory B cells

generated during the primary responses to T dependent antigen or vaccines

T dependent antigen

does a T dependent or independent antigen result in a stronger antibody response?

professional antigen presenting cells

immune cells that specialize in presenting an antigen to a T cell

Natural killer cells

agranular leukocytes that destroy cells that don’t express MHC class 1 on their surface

kill virus infected and tumor cells, attack parasites

what cells do NK cells hurt?

protozoans and helminths

what kind of microbes are usually targeted by antibody-dependent cell-mediated cytotoxicity (ADCC)?

they are too large to be phagocytized

why are protozoans and helminths targeted by ADCC?

antibody dependent cell mediated cytotoxicity, ADCC

coats microbes with antibodies, immune cells attach to the antibodies and proceed to kill the pathogen, target cell is lysed by chemicals secreted by the immune cell.

naturally acquired active immunity

antigens enter the body naturally, body induces antibodies and specialized lymphocytes

naturally acquired passive immunity

antibodies pass from mother to fetus via placenta or infant via the mother’s milk

artificially acquired active immunity

antigens are introduced in vaccines; body produced antibodies and specialized lymphocytes

artificially acquired passive immunity

preformed antibodies in immune serum are introduced by injection

naturally acquired active immunity

what kind of adaptive immunity forms from an infection

naturally acquired passive immunity

what kind of adaptive immunity forms transplacental or via colostrum (breastmilk)

artificially acquired active immunity

what kind of adaptive immunity forms from vaccinations?

artificially acquired passive immunity

what kind of adaptive immunity forms from the infusion of antibodies from an immune person?