Antigen Part II

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56 Terms

1
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Antigen-sensitive cells, like lymphocytes, have receptors that do not normally bind to

self-antigens.

2
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Greater differences in molecular structure between a foreign antigen and the body's

own antigens lead to stronger immune responses.

3
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The immunogenicity of a molecule also depends on its degree of foreignness.

4
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Kidney grafts from identical twins are readily accepted due to identical proteins, while

grafts from unrelated individuals or different species are rejected unless

immunosuppressive drugs are used.

5
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Foreign particles are composed of a complex

mixture of proteins, glycoproteins, lipids, and

other components.

6
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Multiple simultaneous immune responses then

targe teach of these components.

7
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Large complex molecules (e.g. proteins) have

surface regions that bind to lymphocyte antigen

receptors and trigger immune responses.

8
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Larger molecules have more epitopes (one

epitope per 5kDa of protein), some more

immunogenic than others.

9
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epitopes or antigenic

determinants.

10
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The most immunogenic are acknowledged while

the rest are ignored. These epitopes are

immunodominant.

11
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Greek haptein (to grasp or fasten)

12
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Small molecules (< 1000 Da) cannot be processed and

presented to the immune system and are non-

immunogenic.

13
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Small molecules that can only bind to larger molecules

to form new epitopes on the larger molecule’s

surface are called haptens.

14
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The larger molecule is called a carrier.

15
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Can cause many drug allergies (drug molecules bind to

normal body proteins).

16
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Many potential haptens so animals combat this by

making diverse antibodies and antigen receptors.

17
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Penniciloyl groups (from penicillin) bind to serum

proteins like albumin. Can cause penicillin

allergies.

18
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Resin (urushiol) of poison ivy plant binds to skin

proteins of person. Lymphocytes attack this and

cause allergic contact dermatitis.

19
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A small molecule that is antigenic but not

immunogenic on its own

20
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Very small (usually < 1 kDa)

21
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Not immunogenic alone; requires carrier

protein to elicit immune response

22
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Yes – can bind specifically to antibodies

23
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Yes – forms a hapten-carrier complex to be

recognized by immune system

24
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Penicillin, urushiol (poison ivy), some drugs

25
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Usually B-cell mediated (humoral) after

conjugation

26
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Important in drug allergies, autoimmune

diseases

27
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A specific part of an antigen that is recognized

by antibodies or T cells

28
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Small portion of a larger antigen (5–20 amino

acids or sugar residues)

29
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Can be immunogenic as part of the whole

antigen

30
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Yes – site that binds specifically to B-cell or T-

cell receptors

31
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No – it is part of the complete antigen

32
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Influenza hemagglutinin epitope, RBD of SARS-

CoV-2 spike protein

33
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Can be B-cell or T-cell mediated depending on

the epitope

34
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Basis for vaccine development and

diagnostic tests

35
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Unrelated molecules have similar epitopes,

causing antibodies for one antigen to react to

the other.

36
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Blood typing (Bacterial cell wall glycoproteins

have carbohydrate side chains similar to

mammalian red blood cell glycoproteins)

37
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FIP (Feline Infectious Peritonitis) and TGE

viruses (Transmissible gastroenteritis)

38
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Brucella abortus and Yersinia enterocolitica

39
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Related animal species may have protein

epitopes with only minor differences with each

other causing antibodies directed at one species

to react in another related species.

40
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Antisera to bovine serum and sheep and goat

serum albumin.

41
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Useful for determining evolutionary

relationships.

42
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Occurs when two different antigens

share a similar epitope

43
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Same or structurally similar epitope

on different antigens

44
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Immune system mistakes one

antigen for another due to shared

structure

45
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Antibody or T-cell receptor

confusion based on epitope mimicry

46
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Often linked to molecular mimicry,

autoimmunity, and vaccines

47
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Higher specificity; based on

structural mimicry

48
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Occurs when two different epitopes

are recognized by the same

antibody

49
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Different epitopes but antibody

binds both (low specificity or

overlap)

50
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Antibody binds unrelated antigens

due to cross-reactive binding

properties

51
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Cross-reactive antibody binding to

multiple distinct antigens

52
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Can explain false positives in

diagnostic tests or off-target effects

53
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Lower specificity; based on antibody

binding flexibility

54
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Type I cross-reaction — where a

shared or similar epitope in different

species' immunoglobulin light chains

leads to recognition by the same

antibody.

55
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The closer the species is genetically

(e.g., cow vs. bison), the more likely

they share structurally similar epitopes

→ higher cross-reactivity.

56
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Antibodies made against one species

might accidentally detect antigens in

another species, leading to false

positives or misinterpretation.