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USMLE Step 1 > Immunology > Flashcards

Immunology Flashcards

1
Q

What cell types are found in the lymph nodes?

A
  • Macrophages: filter and clean out lymphatic fluid
  • Lymphocytes: B and T-cells – activation, proliferation and differentiation
  • Plasma cells producing antibodies
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2
Q

What lymph nodes does the following area drain to?

Head and neck

A

Cervical/Neck

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3
Q

What lymph nodes does the following area drain to?

Upper extremity, breast and skin above umbilicus

A

Axillary nodes

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4
Q

What lymph nodes does the following area drain to?

Dorsolateral foot and posterior calf

A

Popliteal nodes

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5
Q

What lymph nodes does the following area drain to?

Thigh

A

Superficial inguinal nodes

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6
Q

What lymph nodes does the following area drain to?

Lungs

A

Hilar nodes

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7
Q

What lymph nodes does the following area drain to?

Trachea and esophagus

A

Mediastinal nodes

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8
Q

What lymph nodes does the following area drain to?

Stomach, liver, spleen and pancreas

A

Celiac nodes

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9
Q

What lymph nodes does the following area drain to?

Duodenum, jejunum, ileum and colon up to splenic flexure

A

Superior mesenteric nodes

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10
Q

What lymph nodes does the following area drain to?

Splenic flexure to upper rectum

A

Colonic nodes >> Inferior mesenteric nodes

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11
Q

What lymph nodes does the following area drain to?

  • Lower rectum to anal canal above the pectinate line
  • Bladder and prostate
  • Middle third of vagina
A

Internal iliac nodes

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12
Q

What lymph nodes does the following area drain to?

Testes and ovaries

A

Para-aortic nodes

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13
Q

What lymph nodes does the following area drain to?

Anal canal below the pectinate line

A

Superficial inguinal nodes

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14
Q

What lymph nodes does the following area drain to?

Kidneys

A

Para-aortic nodes

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15
Q

What lymph nodes does the following area drain to?

Scrotum

A

Superficial inguinal nodes

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16
Q

What genes code for MHC-I complexes?

A
  • HLA-A
  • HLA-B
  • HLA-C
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17
Q

What genes code for MHC-II complexes?

A
  • HLA-DR
  • HLA-DP
  • HLA-DQ
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18
Q

What are the T-cell surface markers?

A

All T-cells: CD3
T-helper cells: CD4, CD40L (binds to CD40 on B cells)
Cytotoxic T-cells: CD8

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19
Q

Which cells express MHC-I molecules?

A

All cells except RBCs

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20
Q

Which cells express MHC-II molecules?

A

ONLY antigen-presenting cells (APCs)

Therefore, APCs express both MHC-I and MHC-II complexes

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21
Q

What diseases are associated with HLA-B27?

A

Seronegative arthropathies (PAIR)

  • Psoriatic arthritis
  • Ankylosing spondylitis
  • Inflammatory bowel disease
  • Reactive arthritis/Reiter syndrome
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22
Q

What diseases are associated with HLA-DR3?

A
  • Diabetes mellitus type I
  • Systemic lupus erythematosus (SLE)
  • Graves disease
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23
Q

What diseases are associated with HLA-DR4?

A
  • Diabetes mellitus type I
  • Rheumatoid arthritis
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24
Q

What surface molecules are expressed by dendritic (antigen-presenting) cells?

A
  • MHC-I
  • MHC-II
  • B7 (CD80 or CD86): as a co-stimulatory molecule
  • CD40: to allow the binding Th-cell to stimulate other antigen presenting cells
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25
What is the name of a dendritic cell that is scavenging for antigens?
**Peripheral sentinel** \>\> Also known as "immature state" or "antigen-capturing state"
26
How do peripheral sentinels capture antigens?
- Peripheral sentinels = immature dendritic cells/antigen-capturing dendritic cells - By any of these following 3 mechanisms: \>\> Phagocytosis \>\> Receptor-mediated endocytosis \>\> Pinocytosis
27
What is different in an antigen-presenting dendritic cell from an antigen-capturing dendritic cell/peripheral sentinel?
- Increased expression of MHC-II - Increased expression of co-stimulatory molecules (B7 - CD80/CD86)
28
What are the two different types of dendritic cells?
- Langerhans cell: epidermis - Interstitial dendritic cell: interstitium of all tissues **except the brain**
29
What is the pathology of Langerhans cell histiocytosis?
Proliferative disorder of Langerhans dendritic cells -- functionally immature and do not efficiently stimulate primary T lymphocytes via antigen presentation
30
What are the tumour markers for Langerhans cell histiocytosis?
- S-100 - CD1a
31
What is the characteristic microscopic finding for Langerhans cell histiocytosis?
**Birbeck granules** ("tennis rackets") on **_electron_ microscopy**
32
How does Langerhans cell histiocytosis present?
- Lytic bone lesions - Skin rash - Recurrent otitis media with a mass involving the mastoid bone
33
What are 3 cell types that are known for presenting antigens to T cells?
- Macrophages - Dendritic cells - B cells \>\> All three cell types have CD40 as one of their surface markers
34
What is the embryological origin of the thymus?
Third branchial/pharyngeal pouch
35
What is the action of IL-2?
- Proliferation of cytotoxic T-cells - Proliferation of T1 helper cells
36
What is the action of IL-4?
- Stimulates the differentiation to CD8+ cytotoxic T-cells - Stimulates activation and proliferation B-cells for antibody production
37
What is the action of IL-5?
- Proliferation and activation of B-cells for antibody production
38
What is the action of IL-10?
- To inhibit T1 helper cells from activating macrophages and cytotoxic T-cells - To inhibit macrophages
39
What is the action of IL-12?
To stimulate the differentiation of Th0 cells to Th1 cells
40
What is the action of IFN-gamma?
- To stimulate macrophages for phagocytosis - Inhibits proliferation of Th2 cells
41
What cytokines activate Th1 cells, and what cytokines are produced by Th1 cells?
_Activation_: IL-12 _Production_: IL-2, IFN-gamma
42
What cytokines activate Th2 cells and what cytokines do they produce?
_Activation_: IL-4 _Cytokins produced_: - IL-2 - IL-4 - IL-5 - IL-10
43
What cytokines activate macrophages, and what cytokines are produced by it?
_Activation_: IFN-gamma _Production:_ - IL-12 (stimulates Th0 differentiation to Th1, and activates NK cells) - IL-8 (neutrophil chemotactic agent) - Acute phase reactants: IL-1 (fever), IL-6 (fever) and TNF-alpha (septic shock)
44
What is the function of regulatory T-cells?
- Inhibit **B cells** from _producing antibodies_ - Inhibit **Th cells** and **Tc** cells - Produce _IL-10_ and other anti-inflammatory cytokines
45
How do cytotoxic T-cells kill?
**Two mechanisms** ## Footnote 1. Induce the release of _granyme, granulysin and perforin_ from cytotoxic granules 2. Express _Fas ligands_ to Fas receptors on infected cells
46
What cytokines enhance the activity of NK cells?
- IL-2 - IL-12 - IFN-alpha - IFN-beta \>\> IFN-alpha and beta also inhibit nearby cells of the virally infected cell to reduce viral protein synthesis as an anti-viral effect
47
What cytokines do NK cells release?
- IFN-gamma: to activate macrophages
48
What cells do NK cells target?
- Nonspecific activation signal on target cell - Cells with **no Class I MHC on cell surface** \>\> Sometimes virally-infected cells or cancer cells may downregulate their MHC class Is on their surfaces to "hide" from the immune system
49
How do NK cells kill?
1. Release **IFN-gamma** to attract macrophages to the site for phagocytosis 2. Target cells with _no MHC class I molecules_ on their cell surfaces with **granzyme and perforin release** \>\> apoptosis induction 3. Target cells with _nonspecific signals_ with **granzyme and perforin release** \>\> apoptosis induction 4. **Antibody-dependent cell-mediated cytotoxicity (ADCC)** with CD16 -- binds to the constant region of antibodies \>\> induces apoptosis on cells coated with (opsonized) with antibodes --- linkage with the adaptive immunity
50
What surface molecules do NK cells express?
- CD16: regulates antibody-dependent cell-mediated cytotoxicity (ADCC) - CD56
51
What cells express CD16?
- Natural killer cells (NK cells) - Neutrophils - Some macrophages/monocytes
52
Which cytokines inhibit Th1 cells? Which inhibit Th2 cells?
- Th1 cells are inhibited by **IL-10** - Th2 cells are inhibited by **IFN-gamma**
53
Which cytokines are produced by Th1 cells? Which cytokines are produced by Th2 cells?
_Th1 cells_ - IL-2: activates cytotoxic T-cells and Th cells - IFN-gamma: activates macrophages and inhibits Th2 cells _Th2 cells_ - IL-2: activates cytotoxic T-cells and Th cells - IL-4: activates Th2 cells and B cells - IL-5: activates B cells - IL-10: inhibits Th1 cells
54
Name the disease. Anti-IgG Antibodies
Rheumatoid arthritis \>\> Anti-IgG antibodies = rheumatoid factor (RF)
55
Name the disease. Anti-centromere antibody
CREST scleroderma
56
Name the disease. Anti-citrullinated protein antibodies (ACPA)
Rheumatoid arthritis
57
Name the disease. Anti-Scl-70 antibody
Diffuse scleroderma
58
Name the disease. Anti-histone antibody
Drug-induced lupus \>\> **SHIPP** - **S**ulfonamides - **H**ydralazine - **I**soniazid - **P**rocainamide - **P**henytoin
59
Name the disease. Anti-dsDNA antibodies
Systemic lupus erythematosus (SLE), specific for lupus nephritis
60
Name the disease. Anti-DNA topoisomerase antibodies
Diffuse scleroderma
61
Name the disease. Anti-nuclear antibodies (ANA)
Systemic lupus erythematosus
62
Name the disease. Anti-Jo-1 antibodies
Polymyositis and dermatomyositis
63
Name the disease. Anti-Smith antibodies
Systemic lupus erythematosus (SLE)
64
Name the disease. Anti-SSA (anti-Ro) antibodies
Sjogren's syndrome
65
Name the disease. Anti-U1-RNP antibodies
Mixed connective tissue disorder
66
Name the disease. Anti-desmoglein antibody
Pemphigus vulgaris
67
Name the disease. Anti-SSB (anti-La)
Sjogren's syndrome
68
Name the disease. Anti-acetylcholine receptor antibodies
Myasthenia gravis
69
Name the disease. Anti-endomysial (anti-tissue transglutaminase) antibodies
Celiac disease
70
Name the disease. Anti-gliadin antibodies
Celiac disease
71
Name the disease. Anti-mitochondrial antibodies
Primary biliary cirrhosis
72
Name the disease. Anti-smooth muscle antibodies
Autoimmune hepatitis
73
Name the disease. Anti-glutamate decarboxylase
Type I Diabetes Mellitus
74
Name the disease. Anti-thyrotropin receptor antibodies
Graves disease
75
Name the disease. Anti-thyroid peroxidase (TPO) antibodies
Hashimoto's thyroiditis
76
Name the disease. Anti-thyroglobulin antibodies
Hashimoto's thyroiditis, Graves disease
77
Name the disease. Anti-basement membrane antibody
Goodpasture syndrome
78
Name the disease. c-ANCA
Wegener's disease: granulomatosis with polyangiitis
79
Name the disease. p-ANCA
- Microscopic polyangiitis - Pauci-immune crescentic glomerulonephritis - Churg-Strauss syndrome
80
Name some live-attenuated vaccines.
- MMR - VZV (varicella) - Yellow fever - Intranasal influenza - Sabin (oral) polio - Smallpox
81
Name some killed vaccines.
- Hepatitis A - Salk (injected) polio - Injected influenza - Rabies
82
Name 4 diseases treated with passive immunization.
**T**o **B**e **H**ealed **R**apidly ## Footnote - **T**etanus infection/exposure - **B**otulinum infection/exposure - **H**BV infection/exposure - **R**abies infection/exposure
83
Which viral vaccines are potentially dangerous to patients with an egg allergy?
- Influenza - Yellow fever (Maybe MMR - but the egg amount is so tiny it is usually not clinically significant)
84
What are the two most important opsonins in the body?
- IgG - C3b
85
What are the differential diagnoses for serum eosinophilia?
**DNAAACP (DN-triple-A-CP)** ## Footnote - **D**rugs: NSAIDs, penicillins/cephalosporins - **N**eoplasms - **A**llergies, asthma, allergic bronchopulmonary aspergillosis - **A**cute interstitial nephritis - **A**drenal insufficiency - **P**arasites + HIV + Hyper-IgE syndrome + Hypereosinophilic syndrome + Coccidioidomycosis
86
What are the four types of transplant rejection?
- Hyperacute - Acute - Chronic - Graft-versus-host disease
87
What is the function of the spleen?
- Macrophages found in the spleen (marginal zone) destroy dysfunctional RBCs and encapsulated bacteria - Sequester and store platelets and red cells
88
What are the possible causes of asplenia?
- Autoinfarction in sickle cell anemia - Surgical asplenia (splenectomy) due to: \>\> Trauma \>\> Treatment for hereditary spherocytosis
89
What are the microscopic signs of asplenia?
- Howell-Jolly bodies (nuclear remnants) - Target cells - Thrombocytosis
90
What is the monocyte derivative in: Blood, alvoeli and intestines?
Macrophages
91
What is the monocyte derivative in joints?
A cells
92
What is the monocyte derivative in: Connective tissue?
Langerhans cells/Histiocytes
93
What is the monocyte derivative in: The Liver?
Kupffer cells
94
What is the monocyte derivative in: The Kidneys?
Mesangial cells
95
What is the monocyte derivative in: The Brain?
Microglia
96
What is the monocyte derivative in: The Bone?
Osteoclasts
97
What are the surface markers of macrophages?
- MHC-I molecule - MHC-II molecule - B7 costimulatory molecules (CD80/86) - CD40 - **CD14**
98
What is the function of CD14 surface marker?
Binds to LPS endotoxin of gram-negative bacteria \>\> induces macrophages to generate acute phase cytokines
99
What are the acute phase cytokines released by macrophages? What are their functions?
- IL-1: pyrogenic (induces fever) - IL-6: pyrogenic (induces fever) - TNF-alpha: mediates septic shock
100
What are the functions of macrophages?
- **Phagocytose and digest bacteria** \>\> Motivated to phagocytose bacteria that are opsonized by IgG and C3b \>\> Generate oxygen free radicals using _NADPH oxidase_ - Phagocytose cell debris and clean up wounds - Presents antigen - Release numerous cytokines: IL-1, IL-6, TNF-alpha + IL-8 + IL-12 - Form multinucleate giant cells in granulomas
101
What is the mechanism of action of cromolyn? What are its clinical uses?
- Cromolyn inhibits degranulation of mast cells - Used as: \>\> Inhalers in asthmatics \>\> Nasal sprays in allergic rhinitis etc.
102
What are the actions of IL-1, IL-2, IL-3, IL-4 and IL-5 respectively?
**Hot T**-**B****one**St**EA**k ## Footnote - IL-1: **hot** -- fever/pyrogenic - IL-2: **T**-cells activation - IL-3: **B****one** marrow stimulation - IL-4: Ig**E** and IgG production - IL-5: Ig**A** production and eosinophils stimulation
103
What cytokines are secreted by T-cells?
- IL-2: stimulates proliferation of helper and cytotoxic T-cells - IL-3: supports bone marrow stem cell growth (similar to GM-CSF) - IL-4: stimulates B -cell proliferation and production of IgE/IgG, induces Th2 differentiation - IL-5: stimulates B-cell and eosinophils and production of IgA - IL-10: inhibits macrophages and Th1 cells - IFN-gamma: activates macrophages and inhibits Th2 cells
104
What are the functions of IFN-alpha and IFN-beta?
- Help neighbouring cells avoid infection \>\> Inhibit cellular protein synthesis \>\> Encourage **_ribonuclease_** activation that degreades viral mRNA - Activates natural killer (NK) cells
105
What is the function of IL-8?
Neutrophil chemotaxis
106
What are the three important neutrophil chemotactic agents?
- IL-8 from macrophages - C5a from complement - LTB4 from the arachodonic acid pathway (COXes!)
107
What is the function of IL-12?
- Induces Th0 cells to differentiate into Th1 cells - Activates NK cells
108
What is the mechanism of action aldesleukin?
Recombinant IL-2
109
What are the clinical indications for aldesleukin?
- Renal cell carcinoma - Metastatic melanoma
110
What is the mechanism of action of filgrastim and sargramostim?
GM-CSF analogues \>\> stimulates bone marrow (similar to IL-3 action)
111
What is the mechanism of action of oprelvekin?
IL-11 derivative \>\> For treatment of thrombocytopenia
112
What are the clinical indications for IFN-alpha?
- Genital warts - Hepatitis B - Hepatitis C - Kaposi sarcoma - Hairy cell leukemia - Melanoma
113
What are the clinical indications for IFN-beta?
Multiple sclerosis
114
What are the clinical indications for IFN-gamma?
Chronic granulomatous disease
115
When does hyperacute transplant rejection occur? What is the underlying mechanism?
- Within minutes or hours \>\> usually within in the OT - An antibody-mediated **_Type II hypersensitivity_** reaction by **pre-existing** recipient antibodies - Highly preventable by screening and matching!
116
When does acute transplant rejection occur? What is the underlying mechanism?
- In weeks: within the **_first three months_** - **Cell-mediated**: cytotoxic T cells recognize foreign MHC-1 molecules and attack - *Preventable and reversible by **immunosuppressants*** \>\> Cyclosporin \>\> Tacrolimus
117
When does chronic transplant rejection occur? What is the underlying mechanism?
- Months to years - All transplants are bound to fail at some point in time \>\> hopefully long enough! - Mediated BOTH by **T-cells** and **antibodies** \>\> Cytotoxic T cells treat transplant cells as self-cells presenting non-self antigens \>\> Vascular damage and fibrosis - Unlike acute transplant rejection, **chronic transplant rejection is NOT reversible.**
118
What is graft-versus-host disease?
- Usually seen in bone marrow transplants - When grafted T cells (the new immune system from the donor) recognize the recipient's cells as foreign and attack them - The host is recognized as "foreign" by the new bone marrow/immunity
119
How does graft-versus-host disease present?
- Maculopapular rash covering: neck and shoulders, ears and palms \>\> can blister and look like Stevens-Johnson syndrome - Hemolysis - Jaundice - Hepatosplenomegaly - Diarrhea - Nausea and vomiting \>\> Time of onset varies
120
What is the mechanism of action of cyclosporine?
- Bind to **cyclophilin** - The cyclophilin-cyclosporine complex **inhibits calcineurin** - Blocks T-cell activation by **_PREVENTING IL-2 TRANSCRIPTION_**
121
What are the unique side effects of cyclosporine?
- Nephrotoxicity - Hypertension - Gingival hypertrophy - Hirsutism
122
What is the mechanism of action of tacrolimus and pimecrolimus?
- Binds to **FK506 binding protein** - The complex **inhibits calcineurin** - Blocks T-cell activation by **_PREVENTING IL-2 TRANSCRIPTION_**
123
What are the indications for cyclosporine?
- Transplant rejection prophylaxis - Psoriasis - Rheumatoid arthritis
124
What are the indications for tacrolimus and pimecrolimus?
- Topically for eczema - Systemic tacrolimus for transplant rejection prophylaxis
125
What are the unique side effects of tacrolimus?
- Similar to cyclosporine - **+ Neurotoxicity:** headaches, paresthesia - **No gingival hyperplasia or hirsutism**
126
What is the mechanism of action of sirolimus?
- Binds to **FKBP** - Inhibits **mTOR** (mammalian target of rapamycin) - **Prevents IL-2 _SIGNAL TRANSDUCTION_** - Therefore blocks T-cell activation and B-cell differentiation
127
What are the unique side effects of sirolimus?
- Not much... - Anemia, leukopenia, thrombocytopenia - Insulin resistance - Hyperlipidemia \>\> **NOT NEPHROTOXIC**
128
What is the mechanism of action of azathioprine?
- Antimetabolite precursor of **6-mercaptopurine** - Blocks nucleotide synthesis - Inhibits lymphocyte proliferation
129
What are the indications for azathioprine?
- Transplant rejection prophylaxis - Rheumatoid arthritis - Crohn's disease - Glomerulonephritis - Other autoimmune diseases
130
What are the unique side effects of azathioprine?
- Anemia, leukopenia and thrombocytopenia - Degraded by **_xanthine oxidase_** \>\> toxicity of both azathioprine and 6-MP will be increased by concomittant use of **allopurinol**
131
What is the mechanism of action of mycophenolate?
- Inhibits **IMP dehydrogenase** - Prevents the synthesis of **_guanine_** - Prevents rapid proliferation of B cells and T cells
132
What are the indications for mycophenolate?
- Transplant rejection prophylaxis - Lupus nephritis
133
What is the mechanism of action of muromonab?
- Monoclonal antibody - Binds to **_CD3_** of all T cells - Blocks T-cell signal transduction
134
What are the unique side effects of muromonab?
Cytokine release syndrome
135
What is the mechanism of action of daclizumab?
- Monoclonal antibody - Binds to **_CD25**_, which is the _**IL-2 receptor on activated T-cells_** - Prevents T-cell activation from response to IL-2 activation - Similar to the mechanism of sirolimus
136
What is the mechanism of action of thalidomide?
- Affects TNF-alpha
137
What are the unique side effects of thalidomide?
- Phocomelia
138
What are the unique side effects of mycophenolate?
- Increased risk for **lymphoma** - Teratogenic: increased risk for face and ear malformations, first trimester miscarriage
139
Name three anti-TNF-alpha drugs/monoclonal antibody.
- Infliximab - Adalimumab - Entanercept (not a monoclonal antibody -- a decoy receptor)
140
What are the indications for anti-TNF-alpha drugs?
- Seronegative arthropathies \>\> Psoriatic arthritis \>\> Ankylosing spondylitis \>\> Inflammatory bowel disease-associated arthritis \>\> Reiter syndrome/reactive arthritis - Rheumatoid arthritis
141
What is the mechanism of action of infliximab?
Anti-TNF-alpha monoclonal antibody
142
What is the mechanism of action of abciximab?
GPIIb/IIIa inhibitor
143
What is the mechanism of action of adalimumab?
Anti-TNF-alpha monoclonal antibody
144
What is the mechanism of action of trastuzumab?
HER2/neu receptor monoclonal antibody \>\> Also known as Herceptin
145
What are the clinical indications for trastuzumab?
- Breast cancer - Gastric cancer
146
What is the mechanism of action of rituximab?
CD20 monoclonal antibody
147
What are the clinical indications of rituximab?
Non-Hodgkin Lymphoma
148
What is the mechanism of action of omalizumab?
Anti-IgE monoclonal antibody
149
What are the clinical indications for omalizumab?
Poorly-controlled allergic asthma refractory to routine medical treatment
150
What are the X-linked immunodeficiency syndromes - Name 4.
**WA**t**CH** ## Footnote - **W**iskott-Aldrich syndrome - Bruton **A**gammaglobulinemia - **C**hronic granulomatous disease - **H**yper-IgM syndrome
151
Name two B cell deficiencies.
- Bruton Agammaglobulinemia - Selective Immunoglobulin Deficiencies
152
Name four T cell deficiencies.
- Thymic aplasia (DiGeorge syndrome) - Chronic Mucocutaneous Candidiasis - Hyper-IgM syndrome - IL-12 receptor deficiency
153
Name three combined B and T cell deficiencies.
- Severe Combined Immunodeficiency (SCID) - Wiskott-Aldrich syndrome - Ataxia-Telangiectasia
154
Name 4 phagocyte disorders.
- **Chronic Granulomatous Disease (CGD)** \>\> Lack of NADPH oxidase - **Chediak-Higashi Syndrome** \>\> Defective phagocytic lysosome \>\> Defective LYST gene - **Hyperimmunoglobulin E syndrome/Job syndrome** \>\> Deficient IFN-gamma \>\> High levels of IgE and eosinophils - **Leukocyte Adhesion Deficiency Syndrome** \>\> Abnormal integrins \>\> Defective leukocytic extravasation
155
What is the underlying pathophysiology of Bruton Agammaglobulinemia?
- Defective **_tyrosine kinase_** \>\> B-cell deficiency - Low levels of ALL immunoglobulin
156
What are the clinical features of Bruton Agammaglobulinemia?
- Boy: X-linked disease - Recurrent bacterial infections after 6 months (after maternal breastfeeding usually stops)
157
What is the most common type of selective immunoglobulin deficiency?
IgA
158
How common is IgA selective immunoglobulin deficiency?
Common: 1/600 European descent
159
What are the clinical features of IgA selective immunoglobulin deficiency?
- Recurrent lung and sinus infections - Associated with atopy and asthma - **Possible anaphylaxis to blood transfusions and blood products**
160
What is the underlying pathophysiology of DiGeorge syndrome?
- Failure of 3rd and 4th pharyngeal pouchs to develop \>\> 3rd pouch: inferior parathyroid, thymus \>\> 4th pouch: superior parathyroid
161
What are the clinical features of DiGeorge syndrome?
**CATCH-22** ## Footnote - **C**ardiac anomalies: TOF, truncus arteriosus - **A**bnormal facies - **T**hymic aplasia: no mature T-cells, absent thymic shadow - **C**left palate/lip - **H**ypocalcemia: due to lack of parathyroid development \>\> Chvostek's sign: facial spasm upon tapping the cheek \>\> Trousseau's sign: carpopedal sapsm after tightening a BP cuff on the arm
162
What genetic mutation is thymic aplasia associated with?
Chromosome 22q11 deletion
163
What is Chronic Mucocutaneous Candidiasis?
T cell dysfunction + Candida infections
164
What is the treatment for chronic mucocutaneous candidiasis?
Ketoconazole
165
What are the three types of Hyper-IgM syndrome?
- X-linked: no **CD40 ligand** (a problem with T-cells) - Autosomal recessive: no **CD40** (a problem with B-cells) - NEMO deficiency
166
What infections are commonly associated with IL-12 deficiency?
**Mycobacteria** infections
167
What is the underlying pathophysiology of severe combined immunodeficiency (SCID)?
- Defect in **early stem cell differentiation** - Can be caused by at least 7 different gene defects - The most important gene defect to know: **_adenosine deaminase_** deficiency - Only has **NK cells** left
168
What are the clinical features of severe combined immunodeficiency (SCID)?
- Presentation triad: 1. **Severe recurrent infections** \>\> Chronic mucocutaneous candidiasis \>\> Fatal or recurrent RSV, HSV, VZV, measles, flu and/or parainfluenza infections \>\> PCP pneumonia 2. **Chronic diarrhea** 3. **Failure to thrive** - NO thymic shadow on newborn CXR
169
What are the clinical features of Wiskott-Aldrich Syndrome?
**WAITER** ## Footnote - **W.A.**: **W**iskott-**A**ldrich Syndrome - **I**mmunodeficiency: low IgM, _high IgA_ - **T**hrombocytopenia - **E**czema - **R**ecurrent pyogenic infections
170
What are the clinical features of ataxia telangiectasia?
- Cerebellar ataxia - **Poor smooth pursuit of moving target with eyes** - Telangiectasias of the face at \>5 years of age - Radiation sensitivity - Increased risk for acute leukemia and lymphoma +/- increased AFP in children \>8 months of age \>\> Average age of death: 25 years old
171
Which immunoglobulin is deficient in ataxia telangiectasia?
IgA
172
What is the underlying pathophysiology of chronic granulomatous disease?
- Lack of **_NADPH oxidase_** activitiy - Phagocytes cannot produce oxygen free radicals to kill bacteria - Results in impotent phagocytes who can eat but not kill
173
Which organisms are patients with chronic granulomatous disease more susceptible to?
Those with **catalase** ## Footnote - Staphylococcus (aureus) - Escherichia coli - Klebsiella - Aspergillus - Candida
174
How do we diagnose chronic granulomatous disease?
Nitroblue tetrazolium (NBT) test ## Footnote - Normal: **yellow \>\> blue-black oxidation (positive test)** -- see picture - Chronic granulomatous disease: **no colour change (negative test)** \>\> due to lack of NADPH oxidase activity \>\> no oxidation
175
How do we treat chronic granulomatous disease?
- Prophylactic TMP-SMX - IFN-gamma
176
What is the underlying pathophysiology of Chediak-Higashi syndrome?
Defective LYST gene \>\> defective phagocyte lysosomes
177
What is the pathognomic histological feature of Chediak-Higashi syndrome?
Giant cytoplasmic granules in PMNs
178
What are the clinical features of Chediak-Higashi syndrome?
Presentation triad: ## Footnote 1. Partial albinism 2. Recurrent respiratory tract and skin infections 3. Neurologic disorders
179
What is the underlying pathophysiology of HyperIgE syndrome (Job syndrome)?
Defective IFN-gamma production by T-cells \>\> impaired neutrophil chemotaxis
180
What are the clinical features of HyperIgE syndrome?
Presentation triad: ## Footnote 1. Eczema (E for IgE, E for eczema) 2. Recurrent **cold** **Staphylococcus aureus** abscesses (boils!) 3. Coarse facial features \>\> Broad nose \>\> Frontal bossing \>\> Deep-set eyes \>\> "Doughy" skin + Retained primary teeth \>\> **2 rows of teeth + High levels of _IgE_ and _eosinophils_**
181
What is the underlying pathophysiology of leukocyte adhesion deficiency syndrome?
Abnormal integrins \>\> poor leukocyte extravasation
182
What are the clinical features of leukocyte adhesion deficiency syndrome?
**Delayed separation of the umbilical cord**
183
Name the cell type with the following surface protein. CD4
T-helper lymphocytes
184
Name the cell type with the following surface protein. CD14
Macrophages
185
Name the cell type with the following surface protein. CD16
NK cells and macrophages
186
Name the cell type with the following surface protein. CD19
B lymphocytes
187
Name the cell type with the following surface protein. CD3
All T lymphocytes except NK cells
188
Name the cell type with the following surface protein. CD8
Cytotoxic T lymphocytes
189
A child has an immune disroder in which there are repeated Staph abscesses. It is found that the neutrophils fail to respond because the chemotactic stimuli are deficient. What is the most likely diagnosis?
Hyperimmunoglobulin E syndrome (Job syndrome)
190
Name the immune deficiency. Anaphylaxis on exposure to blood products with IgA
Selective IgA (immunoglobulin) deficiency
191
Name the immune deficiency. Coarse facial features, abscesses and eczema
Hyper-IgE/Job syndrome
192
Name the immune deficiency. Thrombocytopenia, purpura, infections and eczema
Wiskott-Aldrich Syndrome
193
Name the immune deficiency. Delayed separation of the umbilicus
Leukocyte adhesion deficiency syndrome
194
Name the immune deficiency. Neuro defects, partial albinism, recurrent infections
Chediak-Higashi Syndrome
195
Name the disorder. Anti-endomysial antibodies
Celiac disease
196
Name the disorder. Anti-thyroglobulin antibodies
Hashimoto's thyroiditis
197
Name the disorder. Anti-smooth muscle antibodies
Autoimmune hepatitis

USMLE Step 1 (14 decks)

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