Med Micro Quiz 6 Study Guide

what is the purpose of T cells and cell-mediated immunity?

to control intracellular infections

what do T cells have that bind antigens?

they have receptors on their surfaces

T cells are not what?

antibodies!

T cells bind antigens presented on the surface of what cells?

antigen-presenting cells (phagocytes and B cells)

once activated, what do T cells do?

they proliferate and differentiate (similar to B cells)

activated T cells do what to themselves?

they clone themselves, then differentiate into memory cells and other T cell classes

antigens are presented to T cells by what?

APCs

antigens are bound to T cells by what?

T cell receptors (TCR)

after activation, what do proliferating T helper cells do?

they release cytokines that affect T cytotoxic cell proliferation

what is the function of differentiated various T helper subclasses (aka effector cells)?

activate B cells, T cytotoxic cells, macrophages, and other white blood cells

what is the function of differentiated memory T helper and cytotoxic cells (aka memory cells)?

long-lived cells that remain in lymphatic tissues; quickly mount immune response upon re-exposure

what is the function of differentiated various T cytotoxic subclasses (aka effector cells)?

seek and destroy cells infected with intracellular pathogens and cancer cells; activate macrophages

when APCs display antigens on their surfaces to T cells, what is stimulated?

their proliferation and differentiation

what do helper T cells display?

the surface receptor, CD4

what do helper T cells do to other cells?

they activate/stimulate or suppress other cells, such as phagocytes (especially macrophages) and cytotoxic T cells

helper T cells help activate what cells?

B cells, in order to make antibodies

what kills off helper T cells?

HIV

what do cytotoxic T cells display?

the surface receptor, CD8

what do cytotoxic T cells do?

they kill cells infected with pathogens, such as virally-infected cells

what do cytotoxic T cells release?

cytokines, to attract other immune cells

what branch of immunity has the T helper cells?

cellular branch of adaptive immunity

what branch of immunity has the B cells?

humoral branch of adaptive immunity

activated T helper cells release cytokines that can do what?

stimulate or suppress other WBCs

B cells are stimulated by what?

T helper cells

what do activated B cells (plasma cells) secrete?

antibodies

interferons released by cancer cells and/or infected cells attract what?

activated cytotoxic T cells

cytokines released by cytotoxic T cells attract what?

NK cells and macrophages

what do perforins form?

pores

what do granzymes do?

they enter through pores and break down proteins

the targeted cell of a cancer/infected cell undergoes what?

apoptosis

what do macrophages and NK cells do?

they clear the dead cells

what adaptive immunity is mediated with T cells?

the cellular branch

T cells include what types of cells?

T helper and T cytotoxic cells

T helper cells stimulate what?

B cells and other leukocytes

T cytotoxic cells seek and destroy what cells?

cancer cells and cells infected with intracellular pathogens

what are the antigen recognition receptors of T cells?

T cell receptors

do T cells require APCs to become activated?

yes

with T cells, are memory cells made after activation?

yes

with T cells, what MHC protein is present on the cell surface?

MHC I

are T cells considered APCs?

no

what adaptive immunity is mediated by B cells?

humoral branch

B cells include what type of cells?

plasma cells (activated B cells that make antibodies)

what antigen recognition receptors are found on B cells?

B cell receptors, which are secreted as antibodies following B cell activation

do B cells require APCs to become activated?

no

with B cells, are memory cells made after activation?

yes

what is the MHC protein present on the cell surface of B cells?

MHC I and II

are B cells considered APCs?

yes

what is a cytokine storm?

a potentially fatal, uncontrolled immune response

what is a cytokine storm referred to as?

an inappropriate immune response

how does a cytokine storm occur?

certain antigens cause too many immune cells to be sent to the site of infection

what do superantigens do to impact a cytokine storm?

they activate abnormal numbers of T cells by binding non-specifically to the T cell receptors

what is the result of a cytokine storm?

excessive cytokine production

what is an example in which a cytokine storm occurs?

toxic shock toxin of Staphylococcus aereus, certain influenza strains (H5N1)

when a cytokine storm occurs with H5N1 influenza, cytokines go to the lungs and allows for what to occur?

1. lung damage/organ system failure

2. tissue destruction

3. cellular debris

4. inadequate oxygen circulation

cellular immunity includes the elimination of the pathogen/antigen through the actions of what?

T cells

with cellular immunity, the pathogen/antigen is “presented” to the T cells by APCs, such as what?

phagocytes, infected cells, or cancer cells

with humoral immunity, the pathogen/antigen is marked for what?

destruction by antibodies, which are produced by effector B cells

what is the first stage of adaptive immunity?

antigen presentation/recognition

with stage 1 of adaptive immunity, what cells act as APCs?

dendritic cells and certain other WBCs

with stage 1 of adaptive immunity, what type of cells are the main APCs?

dendritic cells

in stage 1 of adaptive immunity, APCs show antigen to what cells?

T cells

with stage 1 of adaptive immunity, B cells do what?

recognize antigens and bind them directly via receptors on their surfaces

with stage 1 of adaptive immunity, what do B cells not require?

do not require APCs to show them antigens

with stage 1 of adaptive immunity, APCs use MHC I or II to do what?

present antigens to T cells

what are the two main classes of MHCs that are important for antigen presentation?

MHC I and MHC II

what does MHC stand for?

major histocompatibility complex

what are MHCs?

proteins on the surface of cells that serve as markers for the immune system

where can you find MHC I?

on all body cells, except RBCs

what does MHC I act as?

the body’s uniform

where can you find MHC II proteins?

only on antigen presenting cells (macrophages, B cells, dendritic cells)

why does having two classes of MHCs make sense?

because antigens can exist in two locations

in stage 1 of adaptive immunity, how are intracellular antigens eliminated?

by killing the host cell

MHC I presents intracellular antigens to what?

cytotoxic T cells (and get killed in the process!)

in stage 1 of adaptive immunity, what happens to extracellular pathogens?

they are directly attacked without the need to kill host cells

in stage 1 of adaptive immunity, why does the MHC II present extracellular antigens to T helper cells?

to help amount an effective antibody response

what does MHC I interact with?

CD8 on cytotoxic T cells

what antigens are presented on MHC I?

intracellular antigens

what does MHC II interact with?

CD4 on T helper cells

what antigens are presented by MHC II?

extracellular antigens

what is stage 2 of adaptive immunity?

lymphocyte activation

with stage 2 of adaptive immunity, upon successful antigen presentation, lymphocytes are activated by what?

a collection of released signaling molecules called cytokines

with stage 2 of adaptive immunity, activated T cells influence what?

B cell activation

what is stage 3 of adaptive immunity?

lymphocyte proliferation and differentiation

with stage 3 of adaptive immunity, activated B and T cells undergo what?

multiple rounds of cell division to proliferate (clonal expansion)

what are effector cells?

cells that engage in the response against the antigen

what are memory cells?

cells that remain in lymphatic tissues to serve as a rapid recognition of the antigen if it’s encountered again later

what is stage 4 of adaptive immunity?

antigen elimination and memory

with stage 4 of adaptive immunity, why do cellular and humoral responses collaborate?

to eliminate the antigen against which they were activated

with stage 4 of adaptive immunity, what happens to the effector cells once the threat of the antigen passes?

the effector cells die off

what is special about memory cells?

they can endure for years in lymphatic tissues

what are naive B cells?

differentiated B cells that have not yet encountered a complementary antigen

what are plasma cells?

fully differentiated B cells that mass produce antibodies to fight current infection

what are memory B cells?

fully differentiated B cells produced during a previous infection that mount an accelerated and amplified response if reinfection with the same organism occurs

what are B cells?

agents of antibody-mediated (humoral) immunity

what are CD4 T cells?

helper T cells

what are T helper cells?

cells that secrete lymphokines to create an immune response

what are CD8 cells?

cytotoxic T cells that destroy infected cells, cancerous cells, and transplanted cells

what are T cells?

agents of cell-mediated immunity and producers of lymphokines

what are natural killer cells?

components of the innate immune system; function with recognizing an antigen; target infected cells, cancerous cells, and transplanted cells

why it is so important to receive vaccinations?

they allow diseases to dwindle down and some are now even non-existent due to the presence of vaccinations