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HB 2 > Adaptive Immunity 1 > Flashcards

Adaptive Immunity 1 Flashcards

1
Q

Describe adaptive immunity.

A

Induced from antigen encounter
Use gene rearrangements to to create different antigen receptors
Memory, specific, self-tolerance

Two branches cell mediated (T and B cells) and humoral (antibody-mediated)

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2
Q

Define antigen

A

Any foreign particle that enters the body such as dust, food and any microorganisms

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3
Q

Define immunogen

A

Substance that induces a specific immune response
All immunogens are antigens but not all antigens are immunogens

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4
Q

Define haptens

A

Small molecules that don’t invoke an immune response on their own but can when coupled to a carrier molecule

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5
Q

Define epitope or antigenic determinant

A

Portion of an antigen that combines with the products of a specific immune response

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6
Q

Define Antibody

A

Specific protein produced in response to an immunogen and that reacts with an antigen

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7
Q

when are receptors for the adaptive immune system generated?

A

During lymphocyte differentiation

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8
Q

Compare B and T cells.

A

B cells: humoral
Attack invaders outside the cell (intact)
Transmembrane receptor: 2 heavy 2 light chains

T cells: cell-mediated
Transmembrane receptor: 2 non-identical proteins
Attacks invaders inside the cells

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9
Q

Compare the effector B cells vs effector T cells.

A

Effector B cells- plasma cells secrete antibodies, secreted form of B cell receptor

Effect T cells- CD4 helper, CD 8 cytotoxic

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10
Q

Where do B and T cells mature, where do they circulate, how do they become effector cells? Which of the two undergo affinity maturation?

A

B (bone marrow), T (thymus): central lymphoid organs
Circulate in blood and peripheral
Effector when they encounter specific antigens that bind to BCR and TCR

When antigen binds:
Cells migrate to lymph nodes and peripheral
Proliferate
Differentiate into effector
B cells undergo affinity maturation to become better fit

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11
Q

Define clonal selection

A

Naive B lymphocytes rearrange DNA in bone marrow resulting in antibodies with unique antigen binding sites

Clonal selection is when an antigen encounters the immune system, at least 1 b cell receptor will react with it

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12
Q

Describe clonal expansion and contraction.

A

Proliferation of lymphocytes after antigen activation

After the antigen is gone, activation ends, contraction of effectors, memory cells remain in bone marrow

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13
Q

Describe clonal deletion and tolerance.

A

During B cells development, deletion of lymphocytes that react with self in primary immune organs (central tolerance)

Deletion of self reactive in peripheral lymphoid organs (peripheral tolerance)

Occurs through apoptosis

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14
Q

What are the receptors on the surface of B cells? What helps to antibody to bind an antigen?

A

Antibodies

Helper T cell

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15
Q

Describe the process of immunoglobulin gene assembly. What proteins carry out this process?

A

Requires DNA recombination and deletion
Each cell has 2 copies of Ig gene, only 1 rearranges and expressed by allergic expression
Requires recognition of recombination signal sequences

RAG-1 and RAG-2 carry out recombination

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16
Q

How do we get antibody diversity? Is B cell differentiation antigen independent or dependent?

A

Many combinations in recombination
Junctional diversity- intro of non-templates nucleotides
Antigen independent rearrangements before encounter
Antigen dependent- affinity maturation

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17
Q

Describe B cell activation.

A

Antigens are recognized by immature B cells
B cells phag and degrade antigens in to peptides in lysosomes
Peptide fragments are carried to B cell surface through MHC 2 and recognized by helper T cells
Helper T cells secrete cytokines that induce B cells to become plasma cells, affinity mature, produce specific antibodies (class switching)

18
Q

Describe when immunoglobulin class switching occurs.

A

Different classes results from genetic recombination
Induced by cytokines from T cell
mRNA splicing is the last step

19
Q

What are the 5 types of immunoglobulin classes (isotypes) in human serum? What are their shapes? What are they named after?

A

IgM (pentamer, largest)
IgG (Y monomer, most common)
IgD (Y monomer)
IgE (Y monomer)
IgA (Y dimer connect by J chain)

Named based on constant heavy chain

20
Q

Describe IgM

A

First responder
Pentamer
Classical complement pathway
Found on B-lymphocytes as B-cell receptors

21
Q

Describe IgG

A

Crosses placenta
Most abundant
Fc region
Activates complement via classical pathway
Binds to both macrophages and neutrophils to enhance phagocytosis
Induce ADCC (Killing of an antibody‐coated target cell through a non-phagocytic process, characterized by the release of cytotoxic granules or by the expression of cell death‐inducing molecules)

22
Q

Describe IgA

A

Made in mucosal associates lymphoid tissue
Body secretions (breast milk)
Blocks attachment of bacteria and viruses to mucous
Dimer
Protested from digestive enzymes
Fc binds to mucous and helps it trap microbes

23
Q

Do we have memory cells on our mucousal membranes?

A

Yes tissue resident memory cells from IgA

24
Q

Describe Ig D

A

Monomer
Found on surface of Blymphocytes as B cells receptor
Role in elimination self reactive auto antibodies

25
Q

Describe IgE

A

Monomer
Triggers allergy symptoms
Fab binds to allergens
Fc binds to mast cells and basophils that mediate allergies
Defender against parasitic worms and arthropods (Fc binds to eosinophils)

26
Q

What antibodies so naive B cells express?

A

IgM (or IgD)

27
Q

Describe the timeframe for generating a pathogen-fighting antibody (primary response) .

A

Lag- 5 to 7 days, antigen recognized as foreign, cells begin to divide and diff

Log- antibody increase, as plasma cells increase

Plateau- antibody synthesis is balanced by antibody decay, no net increase

Decline- Rate of antibody degradation exceeds synthesis, antibody level fall

28
Q

Describe the timetable for the secondary memory response for antibody generation.

A

Lag- shorter than in primary
Log- more rapid, higher antibody levels reached
Steady state phase
Decay- not as rapid and antibody may persist for months, years or even a lifetime

29
Q

How do antibodies neutralize viruses? what vaccine is this included in?

A

Prevent infection
Attach to viruses, prevent viral absorption
Important for preventing reinfection
Coronavirus vaccine

30
Q

How do antibodies protect through opsonization?

A

Antibody and complement facilitate phagocytosis (organism into phagolysosome)
Extracellular killing is antigen is too large
(Virus infected host, transplant cells, cancer cells)

31
Q

Describe how antibodies protect through MAC attacks.

A

MAC attack: antigen-antibody complexes activate complement by the classical pathway
Poke holes in membrane of gram-negative bacteria
Damages viral envelope of enveloped viruses
Cell lysis

32
Q

How do antibodies protect though antibody-dependent. Cellular cytotoxicity (ADCC)?

A

Killing neutralized by non-neutralizing antibodies

Fab region attaches to infected cells and tumor cells
Fc receptor on NK and other cells attach to Fc region of antibodies
NK release perforins granzymes, and chemokines to induce apoptosis

33
Q

How do antibodies protects through recognition and neutralization of toxins?

A

Antitoxin antibodies (IgG), target and neutralize toxins before they can interact with host target cells

34
Q

Describe how antibodies protect from adherence of bacteria?

A

Attach to bacteria and prevent them from adhering to cells

Antibodies are made against pills, capsules and adhesins

35
Q

How do antibodies protect through agglutinate microorganisms?

A

Antibodies with multiple Fab sites (IgM and IgA) link microorganisms together

Complexes are filtered out of lymph and blood and phag more effectively by macrophages, and other phagocytes

36
Q

How do antibodies protest by immobilizing bacteria and Protozoa?

A

Antibodies made against flagella of motile bacteria or Protozoans

37
Q

What are the two methods of inducing an adaptive immune response?

A

Exposure to antigens
Immunization prior to exposure

38
Q

Is immunization passive or active?

A

Can be both

39
Q

describe passive immunization.

A

Transfer of pre-formed antibodies from immune individuals, or by monoclonal antibodies
Instant immunity
Decays rapidly

Ex: rabies vaccine after exposure to rabid animal, newborns through IgG through placenta and IgA through breast milk

40
Q

How does covid vaccine function through passive immunization?

A

Preformed antibodies to SARS-CoV-2 block virus attachment to human ACE2 receptor.

We get it from convalescent plasma: abs to virus from recovered Covid patients.

Administer to infected patients in 1st week during viral replication phase

41
Q

What are monoclonal antibodies?

A

Man-made proteins that act like human antibodies.

42
Q

Describe active immunization.

A

Administration of antigen to raise antibodies in vivo; not
pre-formed.

Requires days to weeks to develop immunity.

Long-lasting (memory).

HB 2 (17 decks)

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