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Immunology-Nicole > Assignment #12 > Flashcards

Assignment #12 Flashcards

1
Q

what is the basic structure of monomeric antibody?

A

two identical light chains covalently linked to two identical heavy chains. Each chain has a variable region and constant region

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2
Q

What are three forms other than monomeric?

A

dimeric, trimeric and pentameric forms

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3
Q

What are 5 antibody isotypes?

A

IgA, IgD, IgE, IgG and IgM with 5 different heavy chain constant regions named Greek letters alpha (α), delta (δ), epsilon (ε), gamma (γ) or mu (μ)

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4
Q

In general terms what does the term subclass mean as it relates to IgG and IgA?

A

Antibodies with small differences in AA sequence in heavy chain constant region, unique properties (IgG1, IgG2, IgG3, IgG4, and IgA1, IgA2)

subclass - variations within an individual

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5
Q

In general terms define the term allotype as it relates to IgG and IgA?

A

polymorphism with a IgG or IgA constant region
Gm and Am respectively
allotype - variations between individuals

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6
Q

What is meant by bifunctional molecule, in regards to an antibody?

A

posses both an antigen-binding capacity and a biological activity region

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7
Q

what is meant by biological activity in regards to an antibody?

A

biological activity in the constant region confers different roles for isotypes.

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8
Q

what is meant by specificity in regards to antibodies?

A

refers to antigen recognition and binding

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9
Q

What are three names for sites within the variable region that bind the epitope?

A

Hypervariable region, complementary determining region (CDR), and paratope

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10
Q

Define the term affinity, in regards to antigen-antibody interaction

A

The strength of the interaction between one antigen binding site and its monovalent antigen. (hydrophobic and ionic)

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11
Q

Define the term avidity in terms of antigen antibody interaction

A

describes the overall binding energy of all antigen-binding sites with antigen

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12
Q

Properties of IgG

A

150kd monomer
75% of the total circulating (highest in circulation)
four subclasses with different biological activities (IgG1, IgG2, IgG3, and IgG4)
20 allotypes (Gm) polymorphisms
Half life about 3 weeks (LONGEST)
All IgGs cross the placenta
Receptors for Fcgamma on monocytes, macrophages, neutrophils and B cells

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13
Q

Roles of IgG

A

Down regulation of B cells following binding to antigen and Fcgamma R
Elimination of microbes by facilitating: opsonization by phagocytes
antibody-dependent cell mediated cytotoxicity (ADCC) by NK cells
neutralization of viruses and toxins
complement activation

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14
Q

Properties of IgM

A

Exists as a monomer on B cells
Pentamer when secreted from plasma cells
15% of total circulating immunoglobulins
Half life 5-7 days
Pentameric form: five covalently attached monomeric units and short J chain and has ten antigen binding sites
Only antibody isotype present on immature B cells

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15
Q

Role of IgM

A

Activate classical pathway of complement (most efficient when bound to antigen)
only one IgM antigen/antigen complex required to activate classical pathway
IgM iso-hemagglutinins responsibile for ABO blood system

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16
Q

Properties and Role of IgD

A

Exists primarily as a membrane bound monomeric form
expressed on naive mature B cells along with IgM
Low detectable serum levels of IgD

17
Q

Properties and Role of IgE

A

monomeric antibody
normal barely detectable in serum
multivalent antigen bound to IgE results in crosslinking of FceRs
Cross linking= release of inflammatory mediators from preformed granules present in mast cells and basophils

18
Q

Properties of IgA

A 
Exists as a monomer, dimer or a trimer 
J chain on dimers and trimers 
IgA half life of one week 
subclasses: IgA1 and IgA 2
Allotypes: Am 
transferred to infants during feeding
activates alternative complement pathway
19
Q

Mechansim of IgA in intestinal lumen

A

B cells activated in lamina propria –> plasma cells
plasma cells secrete dimeric IgA (D-IgA)
D-IgA binds to secretory component (SC) on epithelial cells
D-IgA attached to SC transported in vesicle through epithelial cell (E-cells)
At lumenal side of E cells, SC cleaved; D-IgA retains a piece= D-IgA-SC
SC protects D-IgA-SC from degradation; D-IgA-SC is referred to as secretory IgA

20
Q

Overall role of IgA in the intestinal lumen

A

Binds to and neutralizes pathogens

Binds to microbes before they bind to M cells

21
Q

So where are the secretory vs dimeric IgA located???

A

Secretory IgA —> Lumen

Dimeric IgA —> lamina propria

22
Q

Type O, cell surface antigen? antibody isohemagglutinin? and who can they receive blood from?

A

Cell Surface Antigen –> None
Antibody Isohemmagglutinin —> Anti A and Anti B
Receive blood from individuals who are type O

23
Q

Type A, cell surface antigen? antibody isohemagglutinin? and who can they receive blood from?

A

Cell surface antigen –> A antigens
Antibodies Isohemagglutinin –> Anti B
Receive blood from individuals who are–> Type A

24
Q

Type B, cell surface antigen? antibody isohemagglutinin?and who can they receive blood from?

A

Cell surface antigen –> b antigens
antibodies isohemagglutini –> anti A
receive blood from individuals who are–> type B

25
Q

Type AB, cell surface antigen? antibody isohemagglutinin? and who can they receive blood from?

A

Cell surface antigen —> a and b antigens
antibodies isohemagglutinin –> none
receive blood from individuals who are–> type a or b

26
Q

what tissues are the ABO blood group antigens present on?

A

present on RBCs and most epithelial and endothelial cells

27
Q

who are considered universal donor as well as universal recipient?

A

Donor –> Type O

Recipient –> Type AB

28
Q

What is the antibody isotype of isohemagglutinins?

A

IgM antibodies against the ABO blood group antigens

29
Q

How can antibodies function as antigen?

A

Antibodies are proteins and as such can serve as antigens therefore antibodies can be generated to both the variable and constant regions

30
Q

What was the rationale behind injecting animals with human antibodies?

A

to generate antibodies in the animal that would recognize the Fc portion of human antibodies - this is referred to as anti isotopic antibody

31
Q

Define monoclonal antibody

A

Arise from a single clone of plasma cells; Specificity same and for one epitope

32
Q

Define cross linking

A

One antigen is bound by two antibodies

33
Q

Define cross reactivity

A

antibody generated to one epitope can bind with lower affinity to similar epitope on a different antigen

34
Q

Define polyclonal collection

A

collection of several monoclonal antibodies to an antigen that has several different epitopes

35
Q

Define Idiotope

A

Antigenic determinants in hypervariable regions

36
Q

Define anti-idiotypic antibodies

A

antibodies generated to idiotopes on a single antibody molecule

37
Q

Define anti-isotypic antibodies

A

antibodies generated to epitopes present on the constant region of a heavy chain antibody molecule

Immunology-Nicole (20 decks)

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