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NBME Micro > Immunology: Cellular Components > Flashcards

Immunology: Cellular Components Flashcards

1
Q

A patient has diffuse joint pain, rashes of unclear etiology, and negative serum studies. Which human leukocyte antigen subtype should be considered?

A

HLA-B27; the patient may have 1 of the seronegative arthropathies (PAIR)

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2
Q

What receptor do all MHC molecules bind to on T cells?

A

T-cell receptor (TCR) (and CD4 or CD8 depending on the MHC class)

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3
Q

Name the 3 antigen-presenting cells (APCs).

A

Macrophages, B cells, and dendritic cells (Langerhans cells are a subtype)

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4
Q

How do MHC I and MHC II differ from each other structurally?

A

MHC I has 1 long and 1 short chain; MHC II has 2 equal chains (2 α chains and 2 β chains)

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5
Q

After B-cell activation, what 2 events occur before antibody production?

A

Class switching and affinity maturation

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6
Q

A patient has mucosal hyperpigmentation and hypotension. Which 3 human leukocyte antigen (HLA) subtypes should be considered?

A

HLA-B8, HLA-DR3, and HLA-DR4 (diagnosis: Addison disease)

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7
Q

Which 2 cytokines induce differentiation of Th2 cells?

A

IL-2 and IL-4

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8
Q

What cytokines do Th2 cells secrete?

A

IL-4, IL-5, IL-6, IL-10, and IL-13

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9
Q

Which transcription factor involved in negative T-cell selection is deficient in a patient with autoimmune polyendocrine syndrome-1?

A

Autoimmune regulator (AIRE)

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10
Q

What cytokines do Th17 cells secrete?

A

IL-17, IL-21, and IL-22

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11
Q

What is the rule of 8 regarding T cells and major histocompatibility complex (MHC) binding?

A

MHC II × CD4 = 8; MHC I × CD8 = 8

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12
Q

Th1 and Th2 cells often act to inhibit each other. Which cytokines from Th2 cells inhibit Th1-cell action?

A

IL-4 and IL-10

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13
Q

Which types of organ graft rejections are mediated by T cells?

A

Acute and chronic cellular organ rejection

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14
Q

In the process of B-cell activation, what step occurs after receptor-mediated endocytosis of an antigen?

A

The antigen is presented on MHC II to the T-cell receptor of T helper cells

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15
Q

A man with chronic diarrhea experiences improvement after starting a gluten-free diet. Which HLA subtypes are associated with this disease?

A

HLA-DQ2/DQ8 (diagnosis: celiac disease; I ate [8] too [2] much gluten at Dairy Queen)

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16
Q

Which 2 cytokines induce differentiation of Treg cells?

A

TGF-β and IL-2

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17
Q

B cells undergo somatic hypermutation and plasma cell differentiation in response to antigen. What are the purposes of these 2 functions?

A

Somatic hypermutation optimizes antigen specificity; plasma cell differentiation leads to secretion of specific immunoglobulins

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18
Q

What are the 3 components responsible for adaptive immunity?

A

B cells, T cells, and circulating antibodies

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19
Q

How do T helper cells mediate Ig class switching of B cells?

A

By secreting cytokines

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20
Q

Which 4 autoimmune-related conditions are associated with HLA subtype B27?

A

Psoriatic arthritis, Ankylosing spondylitis, IBD-associated arthritis, and Reactive arthritis (PAIR)

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21
Q

What transporter is involved in loading of viral antigens onto an MHC I molecule?

A

TAP (transporter associated with antigen processing), which delivers the antigen to the rough endoplasmic reticulum for loading onto the MHC I protein

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22
Q

Name the structural protein associated with MHC class I.

A

β2-microglobulin

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23
Q

Th1, Th2, and Th17 cells are specialized descendants of which type of cell?

A

CD4+ helper T cells

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24
Q

Name the receptor on the surface of natural killer cells that is involved in antibody-dependent cytotoxicity.

A

CD16 (which binds to the Fc region of IgG bound to the target cells, thereby activating NK cells)

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25
Q

Which cytokines inhibit the differentiation of Th17 cells?

A

IFN-γ and IL-4

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26
Q

What type of T cell expresses CD3, CD4, CD25, and the transcription factor FOXP3?

A

Regulatory T cell

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27
Q

What is the function of toll-like receptors (TLRs)?

A

As pattern recognition receptors, they recognize pathogen-associated molecular patterns (PAMPs), leading to activation of NF-κB in the innate immune response

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28
Q

Through which mechanism does the adaptive immune system develop a highly specific defense against pathogens?

A

Somatic hypermutation and affinity maturation (variable region); isotype switching (constant region)

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29
Q

Th1 and Th2 cells often act to inhibit each other. Which cytokine from Th1 cells inhibits Th2-cell action?

A

IFN-γ

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30
Q

Are natural killer cells a member of the innate or adaptive immune system?

A

Innate immune system

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31
Q

Which cytokine functions to inhibit the differentiation of helper T cells into Th2 cells?

A

IFN-γ

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32
Q

What is the syndrome associated with genetic deficiency of FOXP3?

A

Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked (IPEX) syndrome

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33
Q

Which 2 cytokines function to inhibit the differentiation of helper T cells into Th1 cells?

A

IL-4 and IL-10

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34
Q

Which cytokine functions to drive differentiation of helper T cells into T regulatory cells?

A

TGF-β and IL-2

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35
Q

Which cytokines function to drive differentiation of helper T cells into Th2 cells?

A

IL-2 and IL-4

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36
Q

A man who had childhood measles develops no disease despite repeat exposure. How does this response work?

A

Memory B and T cells are activated in the adaptive immune response during 1st exposure and release immunoglobulins targeting the measles virus in subsequent exposures

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37
Q

Name the 2 cytokines secreted by Th1 cells.

A

IFN-γ and IL-2

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38
Q

T-cell precursors are produced in the bone marrow. In which organ do they differentiate and mature?

A

Thymus

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39
Q

What is the benefit of germline-encoded target antigen recognition in the innate immune response?

A

It allows innate immunity to be both fast and nonspecific; however, resistance is heritable

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40
Q

What are the primary functions of helper T cells (CD4+ T cells)?

A

Assist B cells in forming antibodies and producing cytokines to recruit phagocytes and activate other leukocytes

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41
Q

Which cytokines function to drive the differentiation of helper T cells into Th1 cells?

A

IL-12, IFN-γ

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42
Q

What is the secondary or co-stimulatory signal in the process of B-cell activation?

A

Binding of CD40 receptor on the B cell to CD40L on the Th cell

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43
Q

A woman has a malar rash, joint pain, proteinuria, and anemia. Which HLA subtypes are associated wth her autoimmune disease?

A

HLA-DR2, HLA-DR3; diagnosis: systemic lupus erythematosis (SLE: 2-3, S-L-E)

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44
Q

Name the antigen-presenting cell responsible for sampling and presenting antigens to activate naive T cells.

A

Dendritic cell

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45
Q

What is the function of MHC receptors?

A

To present antigens to T cells for recognition of foreign particles and initiation of the immune response

46
Q

Which MHC class is involved in mediating the T-cell response in a patient with Streptococcal pneumonia?

A

MHC II (presents exogenously synthesized antigens [eg, bacterial proteins] to CD4+ helper T cells)

47
Q

Toll-like receptor (TLR) activation via pathogen-associated molecular patterns (PAMPs) leads to activation of what cellular protein complex?

A

NF-κB, which functions as a transcription factor

48
Q

A woman has tachycardia, irritability, and exophthalmos. Which 2 human leukocyte antigen (HLA) subtypes are associated with her disease?

A

HLA-B8 and HLA-DR3 (diagnosis: Graves disease)

49
Q

What is the purpose of each of the 2 signals in T-cell activation?

A

Signal 1 (MHC I/II to TCR) presents antigen for T-cell activation; signal 2 (B7 to CD28) induces proliferation and survival

50
Q

B cells and T cells mediate different aspects of the immune response. What do we call these 2 general aspects of immunity?

A

Humoral immunity (B cells) and cell-mediated immunity (T cells)

51
Q

Which cells express major histocompatibility complex (MHC) I on their surface?

A

All nucleated cells, antigen-presenting cells, and platelets (but not RBCs)

52
Q

A patient has elevated lysozymes, complement, CRP, and defensins. Which arm of the immune system (innate or adaptive) is probably involved?

A

Innate immunity

53
Q

Certain vaccines involve memory B cells. What is the purpose of memory B cells?

A

To accelerate the future immune response to antigens

54
Q

How are bacterial antigens loaded onto an MHC II molecule?

A

They are loaded after the release of an invariant chain in an acidified endosome

55
Q

Give an example of a pathogen-associated molecular pattern (PAMP) in viruses and bacteria.

A

Viruses: nucleic acids
Bacteria: lipopolysaccharides and flagellin

56
Q

Which 3 cytokines enhance the activity of natural killer cells?

A

IL-2, IL-12, IFN (α, β, γ)

57
Q

MHC receptors are encoded by what genes?

A

HLA genes (human leukocyte antigen gene complex)

58
Q

In the process of naïve T-cell activation, what serves as the primary signal for Th (CD4+) cell activation?

A

Binding of the MHC II–antigen complex on antigen-presenting cells to the T-cell receptor (TCR) on Th cells

59
Q

Which cells express major histocompatibility complex (MHC) II?

A

Antigen-presenting cells

60
Q

How does the adaptive immune response differ during 1st and 2nd exposures to an antigen?

A

Adaptive immunity is slow to develop on 1st exposure but fast on any subsequent exposures

61
Q

CD8 on cytotoxic T cells binds to what on virus-infected cells?

A

Major histocompatibility complex I (MHC I)

62
Q

What is the function of Th2 cells?

A

To activate eosinophils and promote IgE production for defense against parasites

63
Q

Which 3 HLA loci encode for MHC class II in antigen-presenting cells such as macrophages and B cells?

A

HLA-DP, HLA-DQ, HLA-DR (MHC II have 2 letters)

64
Q

Differentiating T cells undergo negative selection at the thymic medulla. How does this selection occur?

A

T cells that have TCRs with a high affinity for self-antigens will become regulatory T cells or undergo apoptosis

65
Q

A deficiency in Treg cells is associated with which disease?

A

IPEX (immune dysregulation polyendocrinopathy enteropathy X-linked) syndrome

66
Q

After sampling and processing foreign antigens in tissues, how do dendritic cells reach naïve T cells to activate them?

A

Via draining lymph nodes

67
Q

Which 3 autoimmune-related conditions are associated with human leukocyte antigen (HLA) subtype B8?

A

Addison disease, myasthenia gravis, Graves disease (Don’t Be late[8] Dr. Addison, or else you’ll send my patient to the grave).

68
Q

Cytotoxic T cells induce apoptosis in their targets after the release of cytotoxic granules. What do these granules contain?

A

Granzyme B and perforin

69
Q

Cytotoxic T cells work to kill virus-infected, neoplastic, and donor graft cells. Which cell-mediated process allows them to do so?

A

Apoptosis

70
Q

How are self-antigens expressed in the thymus for appropriate negative selection?

A

Autoimmune regulator (AIRE) allows self-antigens to be expressed specifically in the thymus

71
Q

Name the various components of the innate immune system.

A

Neutrophils, monocytes, macrophages, dendritic cells, natural killer cells, complement, secreted enzymes, epithelial barriers

72
Q

After T-cell activation, what is the function of Th and Tc cells, respectively?

A

Th cells produce cytokines, and Tc cells kill cells infected with viruses

73
Q

A 7-year-old patient has polyuria, polydipsia, and high blood sugar. Which 2 HLA subtypes are associated with this patient’s disease?

A

HLA-DR3 and HLA-DR4 (diagnosis: type 1 diabetes mellitus)

74
Q

What cytokines do T regulatory cells secrete?

A

TGF-β, IL-10, and IL-35

75
Q

Which MHC class is primarily involved in mediating the T-cell response in a patient with measles?

A

MHC I; it presents endogenously synthesized antigens (eg, cytosolic or viral proteins) to CD8+ cytotoxic T cells

76
Q

A deficiency in Th17 cells is associated with which disease?

A

Hyper-IgE syndrome

77
Q

What is the primary function of CD8+ cytotoxic T cells?

A

Killing virus-infected cells

78
Q

The ability of monocytes/macrophages to kill microbes is enhanced by the interaction between what cellular marker and cell ligand?

A

CD40 (on macrophages) and CD40L (on T cells)

79
Q

Contrast the receptors used during presentation of an endogenous or cross-presented antigen vs an exogenous antigen.

A

Endogenous antigens are presented on MHC I to CD8+ T cells; exogenous antigens are presented on MHC II to CD4+ T cells

80
Q

A male infant with diabetes is found to have a deficiency of FOXP3. What other conditions might be expected in this patient?

A

Dermatologic conditions (eg, nail dystrophy, dermatitis), enteropathy, and endocrinopathy (this is IPEX syndrome)

81
Q

Name 3 functions of B cells.

A

Antigen recognition (via somatic hypermutation), antibody production (plasma cell differentiation, Ig secretion), maintenance of immunologic memory

82
Q

Which cytokines induce differentiation of helper T cells to Th17 cells?

A

TGF-β and IL-6

83
Q

The initial differentiation of T cells occurs in the thymus. What are the locations of positive and negative selection within the thymus?

A

Thymic cortex for positive selection; thymic medulla for negative selection

84
Q

In the process of naïve T-cell activation, what serves as the primary signal for Tc (CD8+) cell activation?

A

Binding of MHC I–antigen complex on antigen-presenting cells to T-cell receptor (TCR) on Tc cells

85
Q

What 2 signals allow natural killer cells to recognize and kill target cells via cell-mediated immunity?

A

Presence of nonspecific activation signal and absence of MHC I on the target cell surface

86
Q

A patient has weight gain, fatigue, and cold intolerance; anti-thyroid peroxidase antibodies are detected. Which HLA subtypes are associated with this disease?

A

HLA-DR3 and HLA-DR5 (diagnosis: Hashimoto thyroiditis; Hashimoto is an odd Dr [DR3, DR5])

87
Q

What are 3 kinds of cells that cytotoxic T cells kill?

A

Neoplastic, virus-infected, and donor graft cells

88
Q

What serves as the primary signal for B-cell activation?

A

Binding of activated Th cell to the antigen presented on MHC II by B cells

89
Q

Which cytokine that enhances monocyte/macrophage killing of ingested microbes is secreted by Th1 cells?

A

IFN-γ

90
Q

Name the structural protein associated with MHC II.

A

Invariant chain

91
Q

Which 4 autoimmune-related conditions are associated with HLA subtype DR2?

A

DR2 is associated with multiple sclerosis, hay fever, systemic lupus erythematosus, and Goodpasture syndrome (multiple hay pastures are dirty [DR2])

92
Q

How do regulatory T cells maintain specific immune tolerance?

A

They suppress CD4 and CD8 T-cell effector responses

93
Q

What is the function of Th17 cells?

A

To provide immunity against extracellular microbes by potentiating neutrophilic inflammation

94
Q

A deficiency in Th1 cells increases the susceptibility to which type of infections?

A

Mycobacterial infections

95
Q

On the 1st day of a viral infection, a girl has ↑ neutrophils and fever. Is this response a result of the innate or adaptive immune system?

A

The innate immune system, which is responsible for the initial response to a pathogen

96
Q

What is the function of T regulatory cells?

A

To maintain tolerance to self-antigens to prevent autoimmunity

97
Q

Differentiating T cells undergo positive selection at the thymic cortex. How does this selection occur?

A

T cells with T-cell receptors that are able to bind self-MHC on cortical epithelial cells will survive

98
Q

A woman has symmetric swollen metacarpal joints and elbow nodules. Which HLA subtype is associated with her disease?

A

HLA-DR4 (diagnosis: rheumatoid arthritis; there are 4 walls in a “rheum” [room])

99
Q

A patient has ptosis and muscle weakness that worsens with time. Autoantibodies to acetylcholine receptors are detected. What HLA subtype do you suspect?

A

HLA-B8 (diagnosis: myasthenia gravis)

100
Q

A patient has bronze skin, a hematocrit of 60%, diabetes, and elevated iron levels. Which HLA subtype is associated with his disease?

A

HLA-A3 (diagnosis: hA3mochromatosis)

101
Q

In an innate immune response to a virus or bacteria, which receptors are activated?

A

Toll-like receptors, which recognize pathogen-associated molecular patterns (PAMPs)

102
Q

Which 2 enzymes do natural killer cells use to induce apoptosis of tumor cells and virally infected cells?

A

Granzymes and perforin

103
Q

Before the process of B-cell activation can occur, what must happen first?

A

Th-cell activation

104
Q

A man has significant induration 2 days after an intradermal injection of tuberculin from a purified protein derivative (PPD) test. Which immune cells mediate this response?

A

T cells (test result is type IV delayed cell-mediated hypersensitivity)

105
Q

Which receptor on T cells binds to B7 protein (CD80/86) on dendritic cells, serving as a costimulatory signal in T-cell activation?

A

CD28

106
Q

Which cytokine inhibits the differentiation of Treg cells?

A

IL-6

107
Q

Which cytokines work to induce differentiation of Th1 cells?

A

IFN-γ and IL-12

108
Q

What is the function of Th1 cells?

A

To activate macrophages and cytotoxic T cells to kill phagocytosed microbes

109
Q

Which 3 cytokines induce differentiation of Th17 cells?

A

TGF-β, IL-1, and IL-6

110
Q

Which 3 HLA loci encode for MHC class I in all nucleated cells?

A

HLA-A, HLA-B, HLA-C (MHC I loci have 1 letter)

NBME Micro (36 decks)

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