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Molecular Immunology > Lecture 15: Hypersensitivity Type II, III, and IV Reactions > Flashcards

Lecture 15: Hypersensitivity Type II, III, and IV Reactions Flashcards

1
Q

Do Type II hypersensitivity reactions involves soluble or insoluble antigens?

A

Insoluble

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2
Q

True or False: Type II hypersensitivity reactions only occur with involvement of complement activation

A

False
- Type II hypersensitivity reactions occur WITH or WITHOUT complement activation

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3
Q

If a Type II hypersensitivity reaction occurs WITH involvement of complement activation, what is the final outcome?

A

Lysis of cell

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4
Q

If a Type II hypersensitivity reaction occurs WITHOUT involvement of complement activation, what is the final outcome?

A

Antibody opsonization occurs, cell is coated with IgG, IgM, or C3b =>

1) phagocytosis/destruction of cell via: neutrophils/macrophages OR

2) lysis via: ADCC/NK cells

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5
Q

____ system: alloantigens and naturally occuring antibodies
A. Rh System
B. ABO System

A

B. ABO System

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6
Q

What three alleles control the blood groups?

A

A, B, and O

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7
Q

Human serum contains naturally ocurring IgM antibodies called ______ (e.g anti-A, anti-B)

A

isohemaglutinins

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8
Q

True or False: Isohemaglutinins are natural antibodies, in that they occur without deliberate sensitization/immunization against them

A

True

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9
Q

True or False: Newborns lack anti-A and anti-B

A

True
- but acquire with time

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10
Q

Isohemaglutinins are of the ___ isotype
A. IgE
B. IgG
C. IgM
D. IgA

A

C. IgM

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11
Q

AA/AO genotype corresponds to A phenotype.

Which antibodies are present in the sera?
A. Anti-A
B. Anti-B
C. None
D. Anti-A and Anti-B

A

B. Anti-B

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12
Q

BB/BO genotype corresponds to B phenotype.

Which antibodies are present in the sera?
A. Anti-A
B. Anti-B
C. None
D. Anti-A and Anti-B

A

A. Anti-A

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13
Q

AB genotype corresponds to AB phenotype.

Which antibodies are present in the sera?
A. Anti-A
B. Anti-B
C. None
D. Anti-A and Anti-B

A

C. None

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14
Q

OO genotype corresponds to O phenotype. Which antibodies are present in the sera?
A. Anti-A
B. Anti-B
C. None
D. Anti-A and Anti-B

A

D. Anti-A and Anti-B

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15
Q

True or False: Humans have naturally occurring anti-bodies to Rh antigens

A

False - humans do NOT have naturally occurring anti-bodies to Rh antigens

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16
Q

What are two ways in which Rh antibodies can be induced?

A

1) Transfusion
2) Pregnancy

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17
Q

True or False: Rh antigens appear on cell bodies other than the RBC surface

A

False - Rh antigens do not appear on other cell bodies

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18
Q

The presence of a big __ confers Rh+ phenotype

A

D

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19
Q

Under what condition does erythroblastosis fetalis (hemolytic disease of the newborn) typically occur?

A

Rh+ child and Rh- mother

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20
Q

At or about the time of ___, there is a high degree of mixing of maternal and fetal circulation

A

parturition (birth)

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21
Q

Rh+ RBC’s of the infant induce ___ anti-Rh antibodies in the mother
A. IgM
B. IgG
C. IgA

A

B. IgG

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22
Q

True or False: During a mother’s first pregnancy with Rh incompatibility, IgG anti-Rh antibodies cross the placenta, enter fetal circulation, bind to RBC, leading to opsonization

A

False - this occurs during second or subsequent pregnancies

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23
Q

True or False: Rh incompatibility can cause hepato/splenomegaly in infant, as well as anemia, leukopenia, and thrombocytopenia

A

True

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24
Q

True or False: The second and subsequent pregnancies result in an ever-increasing risk of HDN

A

True

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25
Q

Typically, during postpartum, plasma cells make ___. Therefore, in subsequent pregnancy, ____IgG crosses the placenta

A

anti-RhD+; anti-RhD+ IgG

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26
Q

____: IgG anti-Rh from human donors, given to mother within 72 hrs of birth, helps to prevent HDN

A

RhoGam

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27
Q

How does RhoGam work?

A

Binds and removal fetal RBC’s from mother’s immune system prior to initiating immune response against Rh antigen

28
Q

If Rh sensitization occurs, affected fetus may be treated by ____ or ____

A

intrauterine transfusion; exchange transfusion with O-

29
Q

Contaminated blood is an example of which type of transfusion traction?
A. Immune (Hemolytic)
B. Immune (Non-Hemolytic)
C. Non-Immune Reactions

A

C. Non-Immune Reactions

30
Q

If Type B blood is transfused into a patient with Type A blood, this is an example of which type of transfusion reaction?
A. Major Incompatibility
B. Minor Incompatibility
C. Delayed Reaction

A

A. Major Incompatibility

  • Recipient has antibodies against donor
31
Q

If Type B plasma (contains anti-A isohemagglutinin antibody) is transfused into a patient with Type A blood, this is an example of which type of transfusion reaction?
A. Major Incompatibility
B. Minor Incompatibility
C. Delayed Reaction

A

B. Minor Incompatibility

32
Q

In which case does the donor have antibodies against recipient RBC?
A. Major Incompatibility
B. Minor Incompatibility
C. Delayed Reaction

A

B. Minor Incompatibility

33
Q

____ Reaction: occurs when antibodies to donor’s cells form after transfusion

A

Delayed
- Primary immune response (7-10 days)

34
Q

A patient who has received multiple transfusions has antibodies to white blood cells (anti-HLA). Which type of reaction is this?
A. Immune (Non-Hemolytic Transfusion Rx)
B. Immune (Hemolytic)
C. None of the Above
D. Major Incompatibility

A

A. Immune (Non-Hemolytic Transfusion Rx)

35
Q

True or False: Anti-IgA of the IgE class is an example of Immune (Hemolytic) Reaction

A

False - Immune (non-hemolytic transfusion reaction)

36
Q

True or False: The antigens seen in Type 3 hypersensitivity reactions must be insoluble

A

False - antigens in type 3 hypersensitivity reactions must be soluble

37
Q

____: A localized reaction caused by aggregates of antigen and antibody, also known as immune complexes. Soluble antigen becomes insoluble when bound to antibody.

A

Arthus Reaction

38
Q

When does sensitization occur in an Arthus reaction?
A. Immediately
B. 7-10 days
C. Following several consecutive injections

A

C. Following several consecutive injections

  • High serum IgG levels must be achieved
39
Q

In Arthus reactions, eliciting dose of antigen is inject ___ or ___

A

SC; ID
-remains localized

40
Q

In sensitized people, the earliest stages of Arthus reactions are visible within ___ hrs after injection

41
Q

Clinical symptoms of Arthus reaction?

A

1) Swelling at site of injection
2) Redness
3) Hemorrhage at center of lesion (blockage of cap/vessels)
4) Possibly necrotic

42
Q

In Arthus reactions, what immune cell accumulates in capillary and venule walls?

A

Neutrophils

43
Q

True or False: In Arthus reactions, blood flow through small vessels is increased and accompanied by formation of thrombi rich in platelets and leukocytes

A

False - while arthus reactions are often accompanied by formation of thrombi that is rich in platelets and leukocytes, blood flow through small vessels is SLOWED!

44
Q

True or False: In Arthus reactions, there is eventually infiltration by ___ and mononuclear cells

A

eosinophils

45
Q

What are the five steps of Arthus reaction?

A

1) Anti-Ab complex forms at site of antigen localization, in tissue - precipitates out of solution

2) Fc regions of IgG bind C1 = initiates classical complement pathway

3) C5a and C3a is made => increases permeability of blood vessels => edema

4) C5a attracts neutrophils to site

5) Frustrated Phagocytosis

6) Slowed blood flow and thrombi formation

46
Q

What is the role of C5a in Arthus reactions?

A

attracts neutrophils to site

47
Q

In an Arthus reaction, activated ___ may attempt to phagocytose immune complexes that have been deposited along with adjacent tissue, but are unable to due to size.

A

neutrophils

48
Q

In Arthus Reactions, Frusturated Phagocytosis can occur.

In this process, which two cell types release proteases, collagenases, ROS, etc?

A

Platelets and Neutrophils

49
Q

In an Arthus Reaction, thrombi formation + destructive enzyme activity can lead to rupture of vessel wall. As a result of this ___ and ___ can occur.

A

hemorrhage and necrosis of local tissue

50
Q

What is the most common example of an Arthus reaction?

A

Deltoid muscle soreness one gets s/p IM booster immunization

51
Q

Fever, enlarged lymph nodes, rash, painful joints, edema, are all symptoms of:
A. Arthus Rection
B. Serum Sickness
C. Rh Incompatibility

A

B. Serum Sickness

52
Q

____: systemic reaction to antigen, usually antigens administered IV

A

Serum Sickness

53
Q

In a sensitized person, serum sickness syndrome can take hours to ____ days (anamnestic response)

In a non-sensitized person, the primary response can take ___ days

A

3-4 days

7-14 days

54
Q

True or False: Serum Sickness Syndrome cannot occur unless there has been prior sensitization

A

False - Serum Sickness Syndrome can occur WITHOUT prior sensitization in cases when LARGE amounts of antigens are given, which persist in circulation for a long period of time

55
Q

In Serum Sickness Syndrome, where do immune complexes form?

A

1) Blood vessels
2) Glomeruli
3) Joint fluid

56
Q

True or False: Serum Sickness Syndrome has localized responses in ways that are similar to Arthus Reaction

57
Q

In Serum Sickness Syndrome, immune complexes that are formed may be carried directly to the phagocytic cells of the ___ and ____ (reticuloendothelial system)

A

liver; spleen

58
Q

Serum levels, as measured via CH50 in Serum Sickness Syndrome, will reach lowest levels at what point in the disease?
A. Initial onset
B. Height of disease
C. Re-infection phase
D. Recovery phase

A

B. Height of disease

  • This occurs because complement is being fixed and byproducts are released faster than they can be replaced
59
Q

When do symptoms of Serum Sickness Syndrome subside?

A

When free antibody in serum appears

60
Q

True or False: Systemic lupus and RA are also immune complex disorders

61
Q

Which hypersensitivity reaction is cell mediated?

62
Q

In Type 4 hypersensitivity reactions, immune responses are primarily initiated by which cells?

A

Antigen specific T cells

63
Q

In Type 4 hypersensitivity reactions, memory T cells become effector T cells on the ___ exposure to antigen, releasing mediators and cytokines that attract and activate other mononuclear cells and macrophages

64
Q

Why are Type 4 hypersensitivity reactions considered to be delayed?

A

Because it takes 24-48 hrs for reactions to occur in sensitized people

65
Q

What is the key manifestation of Type 4 Hypersensitivity Reaction?

A

Induration (cutaneous or subcutaneous hardening caused by cellular infiltrate)

66
Q

What occurs in Sensitization Stage of Type 4 Hypersensitivity Reaction?

A
  • subcutaneous antigen is processed by APC (Langerhans cell)
  • Th cell recognizes HLA-peptide on APC and differentiates into Th1 cell
67
Q

What occurs in the Elicitation Stage of Type 4 Hypersensitivity Reactions?

A
  • antigen challenge activates specific Th1 cells, which make cytokines (IFN-gamma; MCP-1; TNF-a), leading to activation of macrophages
  • Macrophages accumulate, resulting in local tissue damage

Molecular Immunology (27 decks)

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