Overview Flashcards Preview

Immuno Block 1 > Overview > Flashcards

Flashcards in Overview Deck (108):

Innate Immunity have cells that arise from what?

myeloid progenitor cells


What type of immune cells recognize general features of some pathogens such as repeating subunits that are common to many organisms?

innate immunity


General features that the innate immune system recognize are known as what?

PAMPS - (pathogen-associated molecular patterns)



PAMPS are recognized by what?

PRRs (pattern recognition receptors) that are found on a variety of immune cells


T/F Innate cells recognize signals from the acquired immune response that modulate their responses



How do innate cells help to initiate acquired immune cells?

innate cells (macs, dendritic cells) help by processing and presenting antigen to lymphocytes


What are the cells that mediate acquired immune responses?



How are specific antigens recognized?

the recognition of specific sequences of amino acids, epitope or antigenic determinant


How is immunological memory provide a rapid response upon re-exposure to a pathogen?

upon encounter with specific epitope, lymphocytes produce protein factors (cytokines) to "help" other lymphocytes as well as regulate the activities of innate cells


Where is the site where all elements of the blood are derived from one type of progenitor cell? What is this specific cell called?

Bone marrow

pluripotent hematopoietic stem cell (hSC)


hSC give rise to 2 progenitors that give rise to the rest of the immune system. What are they?

  1. myeloid progenitor
  2. common lymphoid progenitor


The myeloid progenitor is the precursor for what? What type of immunity do these cells provide?

  1. granulocytes
  2. macrophages
  3. dendritic cells
  4. mast cells

Innate immunity


What is the group of cells that make up most of the innate immune system which are polymorphonuclear cells? What are the types of these cells?


  1. neutrophils
  2. eosinophils
  3. basophils


What are phagocytic cells that help activate bacteriocidal mechanisms?



What ar cells that kill antibody-coated parasites?



What type of granulocyte has an unknown function but is very similar to eosinophils?



What cell stems fromthe myeloid progenitor that are scavenger cells that have receptors for a variety of structures that are common to infectious agents?

macrophages (macs)


What cells play an important role in initiation of acquired immune responses? 



The immature circulating form precursors of macs are what?



What are cells that are the most potent stimulators of T cell responses?

What is an important characteristic of these?

dendritic cells

branched, dendritic morphology


What cells take up antigen at the sites of infection/inflammation? Where do they take the antigen after and to what?

dendritic cells take up antigen then return to 2ndary lymphoid tissue to present antignes to naive T cells


What cells stem from myeloid progenitors degranulate to release histamine? What type of hypersensitivity are they associated with?

mast cells

associated with type I hypersensitivity rxns


Describe how macrophages and dendritic cells help initiate the development of acquired immune responses

  1. take up protein antigens
  2. process antigen (cut it into pieces)
  3. present antigen to naive T cells
  4. initiation of acquired immune responses


What cells have IgE receptors on their surface so that their activity can be modulated by acquired immunity?

mast cells


What gives rise to T cells and B cells?

common lymphoid progenitor


What gives tise to the Natural killer cells?

common lymphoid progenitor


Of the cells that come from the common lymphoid progenitor, which express receptor molecules on their surface and which do not?

T cells and B cells express receptor molecules on their surface to allow them to specifically recognize forein antigens

Natural killer cells (NKs) do NOT express antigen specific cell surface receptors


T/F all cells of the immune system originate from the bone marrow


Where do cells of the immune system circulate?

blood and lymphatic system


Describe where lymphocytes are generated and where they mature

  • generated in bone marrow from common lymphoid progenitor cells
  • migrate to lymphoid organs where they differentiate or mature


What are organized tissues where lymphocytes interact with non-lymphoid cells (antigen presenting cells or APC)?

lymphoid organs


What are the 2 main actions that occur in the lymphoid organs?

  1. development
  2. initiate of adaptive immune respones


Where do lymphocytes develop and mature?

central lymphoid organs or primary lymphoid organs


Where do T cells originate? B cells?

Where do T cells mature? B cells?

Both originate in bone marrow

T cells mature in thymus; B cells mature in bone marrow


Where are adaptive immune responses initiated?

peripheral lymphoid organs (2nd lymphoid organs)


What are the 2 actions that take place in the peripheral lymphoid organs?

  1. designed to trap antigens
  2. facilitate presentation of these antigens to lymphocytes


What is the peripheral lymphoid organ that colelcts antigen from the blood? What is its main function?


dispose of dead RBCs


The spleen is made up of red pulp and white pulp. Describe them

red pulp=> site of RBC disposal

white pulp=> lymphocytes surround arterioles entering the spleen

  • white pulp divided into periarteriolar lymphoid sheath (PALS) which contain primarily T cells with flanking B cell corona


What are highly organized lymphoid tissues that collect antigen from lymphatics? Describe the process to reach this peripheral lymphoid organ

lymph nodes

  1. lymphatic vessels collect extracellular fluid from tissues
  2. return it to bloodstream
  3. lymph is continuously produced by filtration of blood


Describe the location of B cells and T cells w/in lymph nodes

B cells localized in follicles

  • T cells distributed more diffusely in surrounding paracortical areas called T cell zones


Where are B cells undergoing intense proliferation? What occurs before this proliferation begins though?

Germinal centers

only following antigenic stimulation with T cell help


What tissues are associated with GALT (gut associated lymph tissue)? What is the function of these tissues?

tonsils, adenoids, appendix, Peyer's patches

function is to capture antigen from eipthelial surfaces of GI tract


What tissue are the most important GALT tissues and have specialized cells called M cells? What is the fxn of M cells?

Peyer's patches

M cells collect antigens along intestinal mucosa


Describe the lymphocyte follicle of Peyer's patches

consists of large central dome of B cells surrounded by smaller numbers of T cells


What types of tissues are similar but diffusely organized lymphoid tissues that protect respiratory epithelium?

BALT (bronchial associated lymph tissue)

MALT (mucosal associated lymph tissue)


What are the 3 most important actions of the innate immune system?

  1. prevent most infectious agents from invading host
  2. clears most infectious  agents
  3. control infections


Describe the link between the primary lymph and 2nd lymph organs

inflammatory responses facilitate uptake of antigen by phagocytes and increase the flow of lymph toward draining lymph tissue 

this facilitates antigen transport to 2nd lymph organ


Describe the central principle of adaptive immunity

clonal selection of lymphocytes

  1. lymphocyte is stimulated by binding of its receptor to its cognate antigen
  2. lymphocyte is activated to proliferate
  3. proliferation gives rise to many new clones that bear identical antigen receptor specificity



T/F lymphocytes express receptor molecules that have highly specific binding characteristics



T/F each antigen-specific receptor expressed on an individual lymphocyte is identical



Describe the lymphocyte repertoire

each lymphocyte can potentially bind to a different specific component of infectious agents


Describe self tolerance

immune system removes most lymphocytes that bear receptors tha bind "self" antigens which will prevent immune system from attach host tissues


How is the diversity of lymphocyte receptor molecules generated?

somatic recombination


Describe the somatic recombination

Ig genes that code for lymphocyte receptors consist of a series of gene segments that are randomly recombined to generate complete coding regions for antigen-binding portions (variable domains) of lymph receptor molecules


What are the 2 antigen receptor of lymphocytes of the acquired immune system?

B cells and T cells


Which antigen receptor lymphocyte are produced and secrete antigen-specific antibody molecules? 

B cells

***humoral immunity or antibody-mediated immunity***


Describe the B cell receptor

surface expressed antibody molecules serve as the B cell receptor and bind to particulate or soluble proteins in native or denatured conformation


What can antibodies(Abs) bind to?

bind to carbohydrates, nucleic acids, small chemical cmpds


B cell receptors have 2 antigen binding sites upon activation that will produce large quantities of antigen specific Abs. What will the result of these bindings produce?

Bind to the specific antigen then
  1. either neutralize the antigen (toxin/infectious)
  2. activate effector mechanisms that remove/destroy antigen


What is the secreted for of the B cell receptor?

antigen specific antibodies


What are lymphocytes that recognize peptide fragments of protein antigens presented on MHC molecules?

T cells


T/F T cells express antigen specific receptor (TCR) on surface and secrete these receptor molecules

What type of binding site is present on these receptors?

False, but do not secrete these receptor molecules

receptors have a single antigen-binding site


Describe B cell activation

  1. (1st signal) BCR binds to cognate antigen
  2. B cell endocytoses the antigen, breaks it into pieces
  3. presents antigen to antigen specific T helper cell
  4. (2nd signal) T helper cell supplies cytokine signal to B cell that activates B cell to proliferate, differentiate, make Abs


Describe T cell activation

specifically recognize peptide fragments of antigens that are presented to T cell by APC (macs, DCs, B cells)
  1. (1st signal) binding of cognate peptide antigen must be followed by
  2. (2nd signal) co-stimulation signal by APC


What are the 3 types of professional APCs?

  1. macrophages
  2. dendritic cells
  3. B cells


What actions must the professional APCs be able to do?

  1. able to take up antigens
  2. antigen processing
  3. antigen presentation (present peptides on surface to T cells)


What are peptide antigens presented on the surface of the APC with?

bound complex with either MHC class I or II molecule


T/F MHC class I and II molecules bind very tightly to many different peptides in a non-specific way



T/F TCR can only bind to peptides that are presented on MHC molecules


When B cells encounter their cognate antigen and become activated, what occurs?

proliferation, differentiation, produce large quantities of antigen specific antibodies


T/F isotypes of Abs have different functions



What action of B cells use antibodies can neutralize some pathogen derived toxins and some pathogens?



Which actions of Abs coat antigens which facilitates the uptake of antigen by phagocytes or NK cells?



Describe complement activation of B cells

some Abs bound to specific antgen serve as a receptor for 1st component of classic complement system

fix complement which facilitates destruction of antigen


Abs play important roles in activation and activity of what 2 innate immunity cells?

activation of NK cells for antibody-dependent cell-mediated cytotoxicity (ADCC)

vital role in activity of mast cells


What are the primary populations of T cells?

CD8 T cells

CD4 T cells


Which T cell recognizes peptide antigen presented on MHC class I molecules? Class II?

MHC class I => CD8

MHC class II=> CD4


Describe how CD8 T cells form armed effectors

once activated via recognition of cognate peptide: MHC I complex and costimulation by APC => CD8 proliferates and progeny cells differentiate into armed effector CD8 T cells


What is the only purpose of armed effector CD8 T cells? What is the other name of these cells?

kill cells that have cognate peptide: MHC I complex on their surface

Cytotoxic T cells or killer T cells


All nucleated cells in the body express what type of MHC molecules? What else do they present? What do these allow?

MHC class I

peptides from intracellular pathogens infecting cells 

These complexes allow for ctyotoxic T cells to target infected cells for destruction


Describe how CD4 T cells secrete cytokines

  1. CD4 T cell encounters cognate peptide: MHC II complex receives proper costimulation
  2. CD4 proliferates and differentiates into armed effector T cells
  3. armed effector T cells secrete cytokines that modulate activity of other immune cells

these are helper T cells


CD4 T cells can differentiate into Th1 and Th2. Describe the actions of these

Th1=> supply cytokine signals to macs to upregulate activities of macs that increase ability to kill ingested bacteria and present peptide antigens

Th2=> promote Ab-mediated immune responses and help with B cell activation to supply cytokine signals that stimulate B cells to produce Abs that help with extraceullar pathogens via neutralization and complement fixation



Which helper T cell helps B cell activation and secrete cytokines that stimulate B cells to produce antibodies for opsonizing pathogens?

Th1 CD4 cells


Which T cell helps stimulate responses that are most effective for destroying intracellular pathogens?

Th1 CD4


Which T cell help B cells produce Abs to eliminate extracellular pathogens? What actions are associated?

Th2 CD4 cells

neutralization and complement fixation


What are the 2 common ways in which the body's immune defenses fail?

  1. evasion and subversion of immune system by pathogens (various mechanisms)
  2. inherited immunodeficiency diseases (single gene mutation can result in profound immunodeficiency)


What are the 3 common unwanted responses of the immune system?

  1. hypersensitivity rxns (over-rxn of immune system such as acute allergies, contact hypersensitivities, immune complex diseases)
  2. autoimmunity - breakdown of safeguards that prevent immune response to self-tissue
  3. graft rejection - by product of safeguards but reject when transplant occurs due to different MHC molecules thus immune system rejects it


What precursor cell is involved in platelet formation and wound repair? What does it produce?




What cell has an important role in clearance of immune complexes from circulation? What type of transport is involved?


oxygen transport


What cell has a primary role to expel parasite pathogens from the body?

mast cells


Describe the correlation of gE receptors and mast cells?

have high affinity IgE receptors on surface that they get from circulation and use them as antigen-specific receptors


What cell is involved in expulsion of parasites from body through release of granules containing histamine and other active agents?

mast cells


What professional APC are involved in activation of T cells and initiation of adaptive immune responses?

Dendritic cells


What is an antigen?

a foreign determinant that can be found on the surface of a pathogen that can be in many forms such as proteins, carbohydrates, and lipids

Pattern recognition receptors


Which immuno cells recognize only protein determinants?

T cells


Which cells of the innate immune system are derived from common lymphoid precursor but bear no antigen specific receptor?

NK cells


Describe the roles of NK cells in both innate and acquire immune responses

  • kill some virally infected cells
  • effector cells of ADCC


What are the 3 roles of the macrophage (macs)?

  • has many pattern-recognition receptors that allow it to    recognize, phagocytose, and destroy microorganisms
  • is also a professional antigen presenting cell

  • has complement and Fc receptors that allow it to find and    destroy opsonized microbes


Where are a majority of immune cells found?

the gut or GALT


Where are T cell and B cell proliferation occuring after an initial immune response triggers an adaptive immune response?

germinal centers


What are the 4 postulates of clonal selection?

  1.  each lymphocyte bears single type of receptor w/ unique specificity
  2. Intxn bw a foreign molecule & lymphocyte receptor capable of binding that molecule w/ high affinity leads to lymphocyte activation
  3. differentiated effector cells derived from activated lymphocyte will bear recptors of identical spec to those of parental cells from which that lymphocyte was derived
  4. ymphocytes bearing receptors specific for ubiquitous self molecules are deleted at earge stage in lymphoid cell development therefore absent from repertoire of mature lymphocytes


T/F only 1 B cell expresses one specific type of Ab



What is a unique mechanism that allows  generation of tremendous  repertoire of antibody and T  cell receptor specificities?

somatic recombination


Describe the activation of B cells and the signals resulting from activation of B cells?

CD4 or Th cells recognize complex of peptide antigen with MHC II and activates B cell

Effector Th2 cells interact w/ antigen-specific B cells in lymphoid tissue


What signals result in activation of T cells?

Naive CD4 T cell recognizes peptide + MHC II

Naive CD8 T cell recognizes peptide + MHC I


What is the most important function of Abs?

coating for opsonization


How do Killer T cells Help Fight Infection?

cytotoxic T cell recognizes complex of viral peptide with MHC I and kills infected cell


Describe the process which Th1 cells kill intravesicular bacteria

Th1 cell and infected macs come together

T cell binds to a, and acitvates macrophage

kill bacteria