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IHO Week 5 > Diseases of the Immune System 2 - Nelson > Flashcards

Diseases of the Immune System 2 - Nelson Flashcards

1
Q

Define Autoimmune Disease

A

Immune-mediated inflammatory disease in which tissue and cell injury are due to immune reactions to self-antigens.

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2
Q

What is the key underlying immune defect in autoimmune diseases?

A

Results from the loss of self-tolerance and activation of self-reactive lymphocytes

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3
Q

What are immune reactions mediated by?

A

Autoantibodies (does not always indicate autoimmune disease)
Immune Complexes
T-Cells

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4
Q

State the two key factors that combined together lead to autoimmune disease.

A

Environmental triggers

Inheritance of susceptibility genes

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5
Q

Describe some of the ways that infections can cause autoimmunity.

A 
Infections may up-regulate the expression of co-stimulators on APC’s.
Molecular Mimicry 
Viruses (EBV, HIV) 
Tissue injury 
Hygiene Hypothesis
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6
Q

How does Molecular Mimicry cause autoimmunity?

A

Offending organism expresses antigens that have the same amino acid sequence of self-antigens

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7
Q

How do viruses (EBV, HIV) cause autoimmunity?

A

Causes polyclonal B-Lymphocyte activation

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8
Q

How does tissue injury cause autoimmunity?

A

Due to the infection releasing self-antigens and structurally altering self-antigens

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9
Q

How does the Hygiene Hypothesis contribute to autoimmunity?

A

As infections become better controlled, autoimmune diseases are increasing.

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10
Q

Describe the typical clinical course of untreated autoimmune disease.

A

Autoimmune diseases may be directed at a specific organ or tissue, resulting in organ specific disease, or may be directed at widespread antigens, resulting in systemic or generalized disease; tend to be progressive.

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11
Q

Define Systemic Lupus Erythematosis (SLE).

A

Autoimmune disease involving multiple organs, characterized by the formation of multiple autoantibodies, particularly ANAs, in which injury is caused mainly by deposition of immune complexes and binding of antibodies to various cells and tissues.

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12
Q

Describe the underlying pathologic mechanism SLE.

A

Fundamental defect is the failure of mechanisms to maintain self-tolerance

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13
Q

What autoantibodies are present in SLE?

A

Anti-nuclear Antibodies (ANA), ADNA/dsDNA and Smith (Sm) antigen are virtually diagnostic.
Others: RIB (Ribosome P Antibodies), IgG

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14
Q

Most of the systemic lesions of SLE are caused by what?

A

Immune complex deposition

– Type III Hypersensitivity

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15
Q

What type of hypersensitivity are autoantibodies directed against red cells, platelets, and white cells, eventually resulting in cytopenias?

A

Type II Hypersensitivity

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16
Q

What are the potential complications of the presence of anti-phospholipid antibodies in SLE?

A

May produce a false positive syphilis test

Can prolong the partial thromboplastin time (lupus anticoagulant)

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17
Q

How do secondary anti-phospholipid antibody syndrome present?

A

Hypercoagulable state
Venous and arterial thrombosis
Spontaneous miscarriages
Cerebral ischemia

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18
Q

Why can SLE involve multiple organ systems?

A

Susceptibility genes interfere with the maintenance of self-tolerance and external triggers lead to persistence of nuclear antigens → antibody response against self-nuclear antigens

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19
Q

Describe some of the key clinical and pathologic skin features in SLE.

A

Clinical: Erythema in light exposed areas
Pathologic: IC deposition at dermoepidermal junctions

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20
Q

Describe some of the key pathologic kidney features in SLE.

A

Pathologic: IC deposition in glomeruli, tubular or peritubular capillary basement membrane, or larger blood vessels

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21
Q

Describe some of the key pathologic joint features in SLE.

A

Pathologic: non-erosive, non-deforming small joint involvement

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22
Q

Describe some of the key pathologic hematologic system features in SLE.

A

Pathologic: Fibrinous pericarditis, non-bacterial endocarditis, accelerated coronary atherosclerosis in long-term disease

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23
Q

Describe some of the key clinical lung features in SLE.

A

Pleuritis, pleural effusion, interstitial fibrosis

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24
Q

SOAP BRAIN MD = clinical features of SLE

A 
Serositis
Oral Ulcers
Arthritis
Photosensitivity, Pulmonary Fibrosis
Blood Cells
Renal, Raynauds
ANA
Immunologic (Anti-Sm, Anti-dsDNA)
Neuropsych
Malar Rash
Discoid Rash
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25
Q

Define Rheumatoid Arthritis

A

Rheumatoid arthritis is a chronic systemic inflammatory disorder that primarily attacks the joints, producing a non-suppurative proliferative and inflammatory synovitis that often progresses to destruction of the articular cartilage and ankylosis of the joints.

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26
Q

Describe the underlying pathologic mechanism in rheumatoid arthritis.

A

Uncertain Pathogenesis, thought to be caused by exposure to an arthritogenic antigen in a genetically predisposed individual → breakdown of immunological self-tolerance and chronic inflammation reaction

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27
Q

Describe the pathologic findings seen in the involved joints.

A

Marked chronic papillary synovitis; dense chronic inflammatory infiltrate rich in plasma cells

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28
Q

Describe the pathologic findings seen in rheumatoid nodules.

A

Area of central fibrinoid necrosis surrounded by a palisade of macrophages and scattered chronic inflammatory cells

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29
Q

What autoantibodies are present in rheumatoid arthritis?

A

CCPs (citrullinated peptides), which are produced during inflammation, also IgG

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30
Q

Describe the typical clinical findings and symptoms of Sjogren syndrome.

A

Dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia) resulting from autoimmune, immunologically mediated destruction of lacrimal and salivary glands; common in middle aged women

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31
Q

Describe the underlying pathogenesis of Sjogren syndrome.

A

Unknown; thought to be related to T and B cell activation in genetically susceptible individuals
– possible trigger: viral infection of salivary glands

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32
Q

What are the two types of Sjogren syndrome?

A

Primary Sjogren Syndrome - isolated disease

Secondary Sjogren Syndrome - associated with another autoimmune disorder

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33
Q

Describe the underlying pathology of Sjogren syndrome

A

Lymphocytic inflammation involving lacrimal and salivary glands, followed by fibrosis and gland atrophy as the disease develops
May also see parotid gland enlargement

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34
Q

What type of neoplasm is associated with Sjogren syndrome?

A

Increased risk for development of MALT lymphoma

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35
Q

What antibodies are present in Sjogren syndrome?

A

Ribonucleoproteins SS-A/Ro and SS-B/La Antibodies

36
Q

Define Systemic Sclerosis (Scleroderma)

A

A chronic disease characterized by chronic inflammation with widespread damage to small blood vessels and progressive interstitial and perivascular fibrosis of the skin and multiple organs; occurs in adults; 3:1 F:M ratio

37
Q

Describe Diffuse Scleroderma.

A

Widespread skin involvement with rapid and early visceral involvement

38
Q

Describe Limited Scleroderma.

A

Skin involvement confined to the fingers, forearms, and face with late visceral involvement; some develop CREST syndrome

39
Q

What is CREST syndrome?

A

Anti-Centromere Antibodies
Calcinosis
Raynaud’s phenomenon - exaggerated vasospastic response to cold or emotional stress; discoloration of fingers, toes
Esophageal dysmotility
Sclerodactyly - extensive subcutaneous fibrosis due to loss of blood supply
Talengiectasia

40
Q

What antibodies are present in Systemic Sclerosis (Scleroderma)?

A

Scl-70 DNA Topoisomerase 1

With CREST syndrome: Anti-CATU (anti-centromere antibodies)

41
Q

What are the typical skin clinical and pathologic findings in Systemic Sclerosis (scleroderma)?

A

Sclerotic atrophy and sclerosis (sclerodactyly) in distal fingers and extending proximally
Can involve the face
Extensive dystrophic calcification in subcutaneous fat

42
Q

What are the typical GI tract clinical and pathologic findings in Systemic Sclerosis (scleroderma)?

A

Esophageal fibrosis resulting in dysmotility with dysphagia and reflux; small bowel involvement resulting in loss of villi and dysmotility with malabsorption, cramps, and diarrhea

43
Q

What are the typical lung clinical and pathologic findings in Systemic Sclerosis (scleroderma)?

A

Interstitial fibrosis

**Respiratory failure is the most common cause of death

44
Q

What are the typical musculoskeletal system clinical and pathologic findings in Systemic Sclerosis (scleroderma)?

A

Non-destructive arthritis; Inflammatory myositis

45
Q

What are the typical kidney clinical and pathologic findings in Systemic Sclerosis (scleroderma)?

A

Vascular thickening; hypertension

46
Q

Define Dermatomyositis

A

Autoimmune disease with immunologic injury and damage to small blood vessels and capillaries in the skeletal muscle, along with skin involvement and characteristic skin rash

47
Q

What is the clinical presentation of Dermatomyositis?

A

Muscle weakness (proximal and symmetric) and skin rash; underlying malignancy in 15-20% of patients; elevated creatine kinase (treated with immunosuppressive drugs)

48
Q

What is the clinical presentation of Polymyositis?

A

Muscle and systemic involvement similar to dermatomyositis, but lack of skin involvement; elevated creatine kinase (treated with immunosuppressive drugs)

49
Q

What autoantibodies are seen in Polymyositis?

A

Anti-Jo1, which is directed against histidyl t-RNA synthetase

50
Q

What is the pathogenesis of Polymyositis?

A

Caused by immunologic injury to muscle by activated CD8+ cytotoxic T-Cells; muscles = lymphocytic inflammation; no vascular injury

51
Q

Define Mixed Connective Tissue Disease (MCTD).

A

Mixed Connective Tissue Disease is an overlap of autoimmune disease with the presence of the distinctive anti-U1-RNP antibody

52
Q

What is a primary immunodeficiency?

A

Congenital, genetically determined deficiency affecting T or B-Cells or defense mechanisms that presents in infancy between 6-24 months with multiple recurrent infections

53
Q

What is a secondary immunodeficiency?

A

Secondary to another disease such as cancer, infection, malnutrition, immunosuppression, irradiation, chemo

54
Q

Describe the pathogenic defect in X-Linked Aggammaglobulinemia (Burton’s Aggammaglobulinemia)

A

Failure of B-Cell precursors (Pro-B and Pre-B cells) to develop into mature B-cells; maturational defect due to X-linked mutation which codes for cytoplasmic Bruton tyrosine kinase (Btk)

55
Q

What are the laboratory findings for X-Linked Aggammaglobulinemia (Burton’s Aggammaglobulinemia)?

A

Decreased or absent B cells in peripheral blood, decreased/absent Ig, no plasma cells, underdeveloped germinal centers in lymph nodes and Peyer’s patches

56
Q

What are the characteristic diagnostic symptoms of X-Linked Aggammaglobulinemia (Burton’s Aggammaglobulinemia)?

A

X-Linked: Seen almost entirely in males

Patients present with recurrent sinopulmonary bacterial infections at 6 months of age

57
Q

Describe the pathogenic defect in Common Variable Immunodeficiency.

A

Heterogenous group of disorders characterized by failure of B cells to differentiate into plasma cells → Decreased Ig production (hypogammaglobulinemia)

58
Q

What are the laboratory findings for Common Variable Immunodeficiency?

A

Normal numbers of B cells in blood; no plasma cells seen

B cell lymphoid areas (germinal centers) are hyperplastic

59
Q

What are the characteristic diagnostic symptoms of Common Variable Immunodeficiency?

A

Sporadic and inherited forms of disease, both sexes affected equally, symptoms later onset in childhood or adolescence/young adults
Increased risk of lymphomas and gastric cancers

60
Q

Describe the pathogenic defect in Isolated IgA Deficiency.

A

Failure of B-Cells to differentiate into IgA producing cells

61
Q

What are the laboratory findings in Isolated IgA Deficiency?

A

Low serum and secretory IgA levels

62
Q

What are the characteristic diagnostic symptoms of Isolated IgA Deficiency?

A

European descent; sinopulmonary infections and diarrhea; commonly also have deficiency of IgG2 and IgG4; respiratory tract allergies
Increased risk of AI disease, anaphylactic reactions to blood transfusions

63
Q

Describe the pathogenic defect in DiGeorge Syndrome (Thymic Hypoplasia).

A

T cell deficiency due to failure of development of the 3rd and 4th pharyngeal pouches; variable loss of T-Cell mediated immunity due to lack of thymus, tetany, heart defects and facial abnormalities

64
Q

Define tetany.

A

Lack of parathyroid glands

65
Q

What is the cause of DiGeorge Syndrome?

A

Sporadic deletion of a gene on chromosome 22q11; not familial

66
Q

What are the laboratory findings of DiGeorge Syndrome?

A

Low levels of T-Cells in peripheral blood, T-cells in lymph nodes and spleen depleted

67
Q

Describe the pathogenic defect in Hyper-IgM Syndrome

A

Patients are able to make IgM, but are deficient in their ability to make IgG, IgA, and IgE antibodies (defect in immunoglobulin class switching)

68
Q

What are the laboratory findings of Hyper-IgM Syndrome?

A

normal IgM levels, little IgG, no IgA or IgE

69
Q

What is the cause of Hyper-IgM Syndrome?

A

70% of individuals have X-linked recessive mutations in the gene encoding CD40 ligand → can’t deliver class-switching signal

70
Q

Describe the pathogenic defect in SCID (Severe Combined Immunodeficiency)

A

Profound defects of both humoral and cell-mediated immunity; without hematopoietic cell transplantation, death occurs within a year.

71
Q

What is the cause of SCID?

A

Most commonly, X-linked due to a mutation in the gene encoding the common gamma-chain subunit of cytokine receptors; Sometimes autosomal recessive deficiency of adenosine deaminase (ADA)

72
Q

When the gamma-chain subunit of cytokine receptors is mutated, what happens to cytokine signaling and T-cell development?

A

Reduced cytokine signaling and T-cell development markedly impaired

73
Q

If cytokine receptors are mutated, then what is the consequence for T-Cells and NK Cells?

A

T cells and NK cells are decreased and Ab synthesis is severely impaired due to lack of T helper cells

74
Q

What is the cause and symptoms of Immunodeficiency with Thrombocytopenia and Eczema (Wiskott-Aldrich Syndrome)?

A

X-Linked Recessive Disorder with Thrombocytopenia, eczema, vulnerability to recurrent infection (deletion of B and T cells)

75
Q

Describe the pathologic defect in Wiskott-Aldrich Syndrome

A

Mutations in gene encoding Wiskott-Aldrich syndrome protein (WASP) located on short arm of x-chromosome, believed to link cell membrane receptors, including antigen receptors –> causing defects in cell migration and signal transduction

76
Q

What are the laboratory findings in Wiskott-Aldrich Syndrome?

A

Depletion in T-Cells with variable loss of cell-mediated immunity; antibody production to polysaccharide antigens is absent with low levels of serum IgM, IgG normal, IgA and IgE elevated

77
Q

Describe the pathogenic defect in X-Linked Lymphoproliferative Syndrome

A

Inability to eliminate EBV, leading to severe/sometimes fatal infectious mononucleosis and B-cell lymphomas; most cases due to mutations in gene encoding a mlc called SLAM-associated protein (involved in activation of NK cells and T and B cells)

78
Q

Describe the pathogenic defect in Chediak-Higashi Syndrome

A

Defective fusion of phagosomes and lysosomes in phagocytes

79
Q

What are the laboratory findings of Chediak-Higashi Syndrome?

A

Peripheral smear for pathognomonic giant cytoplasmic granules in leukocytes

80
Q

What are the causes of secondary immune deficiency?

A 
Immunosuppressive Therapy
  1) Cytotoxic therapy for Malignancy
  2) Treatment of autoimmune disease
  3) Bone marrow ablation prior to transplantation
  4) Treatment of GVHD
  5) Treatment following solid organ transplant
Microbial Infection (HIV/AIDS)
Malignancy
  1) Hodgkins disease, CLL (hypogammaglobulinemia)
  2) Multiple myeloma
  3) Malignancy of solid tumors (tumor-derived immunosuppressive factors)
Disorders of Biochemical Homeostasis
  1) Diabetes
  2) Renal insufficiency/dialysis
  3) Hepatic insufficiency/cirrhosis
  4) Malnutrition 
Autoimmune diseases
Severe Burn Injury
Exposure to Radiation/Toxic Chemicals
Asplenia/Hyposplenism (loss of splenic macrophages)
81
Q

What are the three ways that one could suspect a patient has an immunodeficiency?

A

Clinical History
Opportunisitic Infection from a Signature Organism
Repeated Infections

82
Q

What laboratory tests you would order to assess B-cell function?

A

Immunoglobulin Levels to assess for antibody deficiencies

83
Q

What laboratory tests you would order to assess T-cell function?

A

Flow Cytometry for cellular immunity

84
Q

What laboratory tests you would order to assess phagocytic function?

A

Peripheral blood smear, genetic tests, test neutrophil function

85
Q

What laboratory tests you would order to assess complement function?

A

Total serum complement (CD50)

IHO Week 5 (5 decks)

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