The Immune Response Flashcards by Jessica Mangan

first line of defence?

intrinsic barriers

How well did you know this?

Not at all

Perfectly

second line of defence?

innate immunity

How well did you know this?

Not at all

Perfectly

third line of defence?

adaptive immunity

How well did you know this?

Not at all

Perfectly

confers protection against a broad spectrum of pathogens through use of surface receptors on phagocytic cells that recognize evolutionary conversed patterns unique to pathogens

the innate immune system (2nd line of defence)

How well did you know this?

Not at all

Perfectly

do not phagocytose pathogens, rather they secrete toxic chemicals or induce apoptosis in target cells

natural killer cells

How well did you know this?

Not at all

Perfectly

a localized response to infection involving vasodilation, increased vascular permeability and mobilization of phagocytes involving: leukocytosis, margination, diapedesis and chemotaxis

inflammation

How well did you know this?

Not at all

Perfectly

It is initiated by release of pyrogens (pyro= fire) which include bacterial toxins and/or components, antigen-antibody complexes or substances released by phagocyte

a fever

How well did you know this?

Not at all

Perfectly

The goal is to eliminate pathogens that may have circumvented or overwhelmed the first 2 lines of defence and to confer protection from new and emergent strains of pathogens

the adaptive immune response (3rd line of defence)

How well did you know this?

Not at all

Perfectly

what are the hallmarks of the adaptive immune response?

specificity (self vs non-self)

- memory

How well did you know this?

Not at all

Perfectly

is the ability to mount a response to a particular pathogen or foreign substance while being able to discriminate between self vs non-self antigens

Specificity

How well did you know this?

Not at all

Perfectly

represents the ability to recall past exposures to specific pathogens and provides the adaptive immune system with the ability to mount an even stronger response to a pathogen upon repeat exposure

Memory

How well did you know this?

Not at all

Perfectly

broad specificity
limited repertoire
lacks memory

innate immune system

How well did you know this?

Not at all

Perfectly

narrow specificity
slow response
memory

adaptive immune system

How well did you know this?

Not at all

Perfectly

represents a loose aggregation of lymphoid tissue that is in a unique position to eliminate pathogens at mucosal surfaces before they spread to the underlying tissues

MALT (mucosal associated lymphoid tissue)

How well did you know this?

Not at all

Perfectly

____ can only recognize antigens that have first been processed by specialized immune cells known as antigen presenting cells or APCs

T-cells

How well did you know this?

Not at all

Perfectly

___ are capable of recognizing unprocessed (or native) antigens

B-cell receptors

How well did you know this?

Not at all

Perfectly

DNA segments in T-cell and B-cell receptor genes are randomly combined to create a vast array of permutations

Somatic recombination

How well did you know this?

Not at all

Perfectly

progressive neurodegenerative disorder involving demyelination of CNS axons

How well did you know this?

Not at all

Perfectly

an endocrine disorder resulting in hyperglycemia due to insulin insufficiency

T1DM

How well did you know this?

Not at all

Perfectly

a neuromuscular disease resulting in progressive weakening or paralysis of skeletal muscle

Myasthenia Gravis (MG)

How well did you know this?

Not at all

Perfectly

a thyroid disorder resulting in overproduction of thyroid hormone (thyroxine) leading to diffuse goitre and exophthalmos

Grave’s Disease

How well did you know this?

Not at all

Perfectly

Auto-antibodies bind IgG, forming immune complexes in synovial joints resulting in synovitis with destruction of articular cartilage and bone

Rheumatoid Arthritis (RA)

How well did you know this?

Not at all

Perfectly

impairment of renal function due to inflammation of glomerular basement membrane

Glomerulonephritis

How well did you know this?

Not at all

Perfectly

Characterized by inflammation involving multiple body systems

Systemic Lupus Erythematosus (SLE)

How well did you know this?

Not at all

Perfectly

___ are more prone to developing SLE

females

Inhibit the early events of antigen processing and cytokine production by macrophages, thereby reducing lymphocyte activation and subsequent autoantibody production

Anti-malarials

are a broad class of therapies that employ a wide variety of products from humans, animals, and microorganisms

Biologics

inhibits a cell survival factor called BLyS (or B-lymphocyte stimulator), which is necessary for B-cell survival.

One specific biologic (a monoclonal antibody preparation called belimumab)

is a cytokine that promotes the survival of regulatory T-helper cells

IL-2

T-cell development begins with a process known as ____

positive selection or MHC restriction

specialized thymic epithelial cells present self-antigens to developing T-cells in the context of MHC.

negative selection or clonal detection

both positive and negative selection occur within the ____

thymus

___ appears to be the main mechanism responsible for preventing B-cell mediated autoimmune responses should autoreactive B-cells make their way out of the bone marrow.

angery

For T-cells and B-cells to become fully activated antigen presenting cells must supply them with ___

additional co-stimulatory molecules

function to inhibit or suppress the activities of autoreactive lymphocytes, thereby contributing to peripheral tolerance and ensuring that autoimmune diseases do not arise.

Regulatory T-cells produced during thymic education

may result if self-antigens that were not present during T-cell and B-cell development suddenly become accessible

autoimmunity

Cytotoxic T-cells are responsible for mediating cellular immunity

CD8+

Helper T-cells aid in the induction of cellular and humoral responses by providing essential signals that drive T-cell and B-cell differentiation and clonal expansion

CD4+

largely secrete a chemical signal called interleukin-2 (IL-2) which helps to fully activate cytotoxic T-cells.

Th1 cells

largely secrete IL-4 which provides the co-stimulatory signal necessary to fully activate B-cells that have come into contact with foreign antigens

Th2 cells

cells secrete IL-17 which activates neutrophils and plays a major role in fighting fungal infections

Th17 cells

Their main function is to suppress adaptive immune responses

Regulatory T-cells

are largely found in the secondary lymphoid tissues

B-cells

when antibodies bind toxins, they often inactivate it through direct or allosteric inhibition of the toxin's active site

Neutralization

each antibody possesses at least two antigen binding sites, hence they are capable of binding more than one antigen, resulting in clumping

agglutination

process of tagging antigens with antibodies to help improve phagocytosis

opsonization

__ on the surface of mast cells, basophils, and eosinophils are capable of binding the stem region of antibodies, which then act as a surface receptor

Fc-receptors

1st antibody produced during an adaptive response

IgM

- Activate compliment - Enhance agglutination - Neutralize toxins, bacteria and viruses

IgM Functions

- most abundant serum antibody (80-85%) | - Longest lasting antibody

IgG

- complement activation - opsonization of pathogens - neutralization of toxin, bacteria and viruses

IgG functions

found in mucosal secretions (milk, tears)

IgA

- confers protection to GI, resp, urinary, and reproductive tracts - agglutination - neutralization of pathogens

IgA functions

implicated in host response to parasites and involved in allergic reactions

IgE

- expressed on surface of B-cells (B-cell receptor) | - thought to participate in B-cell differentiation

IgD

largely reside in the skin and mucus membranes where they are most likely to encounter pathogens

dendritic cells

are considered professional since they are capable of processing extracellular antigens

antigen-presenting cells

are found on virtually all nucleated cells of the body

class I MHC molecules

only found on professional APCs

class II MHC molecules

involves processing of endogenous, cytoplasmic proteins which are then loaded onto MHC I within the endoplasmic reticulum

the MHC I pathway

Essentially, exogenous antigens are taken up by the cell through phagocytosis and processed by combining the resultant phagosome with a lysosome to create phagolysosome

MHC II pathway

Infected- and this is the key here - infected dendritic cells will present antigen via MHC I to cytotoxic T-cells

Step 1- antigen presentation Cellular immunity

- involves helper T-cell differentiation | - For a helper T-cell to become activated, the dendritic cell must present antigen in the context of MHC II.

Step 2- involves helper T-cell differentiation Cellular immunity

- requires both the coupling of MHC I with the T-cell receptor and IL-2 from activated helper T-cells - Once activated, cytotoxic T-cells will proliferate to form identical clones that will either become memory T-cells or more cytotoxic T-cells

Step 3- involves clonal expansion of cytotoxic T-cells Cellular immunity

As clonal expansion proceeds, many of the replicating cytotoxic T-cells will begin to secrete their own IL-2, thereby obviating any need for further dendritic or helper T-cell support

Step 4- involves self-stimulation Cellular immunity

This response is initiated by cross-linking of more than one B-cell receptor by repeating epitopes contained on evolutionarily-conserved structures such as the capsule of the influenza virus, lipopolysaccharide expressed in the outer cell wall of gram-negative bacteria (as shown here), bacterial flagella, and other viral capsids

T-cell independent humoral activation

- the type of antibody produced will change | - involves an alteration in the stem or Fc region of an antibody

class switching

The hallmark of adaptive immunity is ___

immunologic memory

○ Sensitization to antigen (allergen) resulting in production of IgE which primes mast cells, basophils, and eosinophils ○ Subsequent binding of allergen to IgE-receptors of mast cells, basophils and eosinophils induces degranulation with release of histamine ○ Disorders- seasonal allergic rhinitis, conjunctivitis, asthma, acute anaphylaxis (shock)

Type I hypersensitivity reaction

○ Antibodies bind cells and fix complement resulting in cell lysis ○ Disorders- transfusion reaction, hemolytic disease of newborn, drug-induced cytotoxicity

Type II hypersensitivity reaction

○ Deposition of antigen-antibody complexes in joints, tissues, and vessel walls ○ Complement activation and inflammation damage tissues ○ Disorders- systemic lupus erythematosus, serum sickness, rheumatoid arthritis, glomerulonephritis, hypersensitivity pneumonitis

Type III hypersensitivity reaction

○ Host cells destroyed by cytotoxic T-cells ○ Delay reflects time required to initiate cellular response ○ Disorders- contact dermatitis, tuberculin response, graft rejection

Type IV hypersensitivity reaction

is largely due to increased vascular permeability in the mucus membranes of the lower airways

airway swelling

is a direct result of histamine-evoked airway smooth muscle contraction

bronchospasm

is characterized by system wide vasodilation and increased vascular permeability owing to massive combined release of histamine from tissue resident mast cells and basophils present in circulation

Anaphylactic shock

is a blood-borne pathogen that is also present in other bodily fluids including vaginal secretions, semen, and breast milk

HIV

HIV occurs in __ phases

usually occurs 1-3 months following infection and is characterized by detectable levels of anti-HIV antibodies

seroconversion

CD4+ T-cell counts gradually decline as the rate of T-cell death overcomes production

latency period

inhibit elongation of viral DNA by preventing addition of nucleosides

Nucleoside/nucleotide analogs (NRTI/NtRTI)

Bind RT active site to prevent transcription of viral RNA into DNA

Reverse Transcriptase inhibitors (NNRTIs)

Prevent cleavage of viral polypeptides necessary for viral assembly (virus rendered non-infectious)

Protease inhibitors

Block HIV fusion with CD4 | Block CCR5 receptors

Entry inhibitors

Prevent viral DNA integration into host genome

Integrase inhibitors