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Immunology Flashcards

1
Q

HIV 2

A

Specific to Portuguese and West Africans
Less progressive, less immunocompromised with less opportunistic infections
Less responsive to treatment

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2
Q

HIV testing

A

Before 12 weeks
- p24 Antigen < 10 days (rules in but not out)
- HIV RNA or pro-viral DNA

After 12 weeks
- HIV serology
- HIV PCR

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3
Q

Hypersensitivity Reactions

A

Type 1 - IgE mediated
Type 2 - IgG mediated cytotoxicity
Type 3 - Immune Complex Ab-Ag mediated cytotoxicity
Type 4 - T cell mediated excitotoxicity

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4
Q

CCR5 heterozygous individuals

A

CCR5 is a co-receptor for HIV binding (in early infection). A lack of co-receptor CCR5 causes a slower progression or relative protection against HIV infection

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5
Q

HLA B5701 in HIV

A

MHC molecule on CD4 which has higher affinity for CD8 killer cells & are more likely to be able to control there viral load/slower progression of disease. These patients cannot be treated with Abacavir (risk hypersensitivity)

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6
Q

HIV medications with highest risk metabolic syndrome

A

Protease inhibitors “NAVIR”

along with high bilirubin, renal stones and lipodystrophy

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7
Q

Abacavir

A

NRTI
Hypersensitivity reaction in patients with HLA B5701 & risk of cardiovascular events

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8
Q

HIV drugs causing Lipodystrophy

A

Protease inhibitors
Zidovudine (NRTI)

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9
Q

Hepatitis B serology

A
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10
Q

Hepatitis B treatment contraindicated in cirrhosis

A

Peg IFN - should only be used in mild - mod disease (not cirrhosis!)
Can cause psychiatric disturbances and transient cytopenia
Active against Hep D coinfection
contraindicated in pregnancy

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11
Q

Intracranial lesions in HIV

A
  • Toxoplasmosis
  • Progressive multifocal leukoencephalopathy (PML), JC virus
  • Primary Lymphoma
  • Tb
  • Abscess
  • Kaposis (HHV8)
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12
Q

Toxoplasmosis lifecycle and treatment

A

Cat as host for parasite -> cat faces containing Ova ingested by animals -> Undercooked animal meat ingested by Humans -> pass onto fetus

Rx with Pyrimithamine-Sulphadiazine, with folic acid-> inhibits dihydrofolate reductase of plasmodia and thereby blocks the biosynthesis of purines and pyrimidines

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13
Q

CD4+ levels and Infections

A

< 200 PJP
< 100 Toxoplasmosis
< 50 Mycobacterim, CMV

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14
Q

IgM half life

A

7 days

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15
Q

T helper cells

A

Th1 - secretes IFN-gamma to activate macrophages, and induces B cells to produce opsonising IgG Ab’s which promote phagocytosis.

Th2 - secretes IL4, 5, 13 to up regulate IgE class-switching and activation of eosinophils (via IL5). Involved in Allergy and Parasite infections.

Th17 - secretes IL17 and IL22 to up regulate neutrophils and monocytes to target intracellular organisms, bacteria and fungi

TReg - Secretes IL10 and CTLA via FOXp3 transcription factor to suppresses IL2. Has an immunosuppressant role.

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16
Q

Hep B Immune phases

A

Immune Tolerance - HBeAg+, DNA ++, ALT normal
Immune Clearance - HBeAg+, DNA +, ALT high (treat)
Immune Control - HBeAg-, Anti-HBeAb +, DNA low, ALT normal
Immune Escape - HBeAg-, Anti-HBeAb +, DNA high, ALT high (treat)

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17
Q

Contrindication to PEG IFN in Hep B

A
  • Cirrhosis or advanced Hep B (only used or mild-mod hep B)
  • Pregnancy or lactation
  • Neuropsychiatric disorders
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18
Q

Cryptococcus

A

CD4 count < 150
Yeast from bird dropping causing meningitis in HIV and immunocompromised patients
+ Cryptococcal Ag in serum and CSF
Treat with Amphotericin + Flucytosine for 2 weeks, then Fluconazole for 8 weeks

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19
Q

Toxoplasmosis

A

CD4 count < 50
Parasitic infection from Cats
Causes intracranial lesions with toxoplasmosis encephalitis
Toxoplasmosis Serology +
Rx with pyrimethamine-sulphadiazine (anti-parasitic)
Bactrim as prophylaxis CD4 < 100

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20
Q

Opportunistic infections in HIV

A
  • Common bacterial infections, Tb CD4 > 200 (Isoniazid prophylaxis if positive skin or Q-Gold test)
  • PJP < 200 (bactrim prophylaxis)
  • Cryptococcus < 150 (Fluconazole prophylaxis)
  • Toxoplasmosis < 100 (bactrim prophylaxis)
  • CMV, MAC < 50 (Azithromycin prophylaxis)
21
Q

CMV

A

HHV 5
CD4 count < 50
Ulcerative oesophagitis
Pneumonitis
Encephalitis with periventricular enhancement
Colitis
Hepatitis
Donar positive-Recipient negative in SOT
Donar negative - Recipient positive in BMT
“Owl Eyes” on blood film
Rx with Valganciclovir

22
Q

Types of T helper cells

A

Th1 - release IFN-gamma to up regulate IgG production at B cells for opsonisation & NK cells to kill intracellular pathogens. Involved in MS pathogenesis

Th2 - release IL4, 5, 13 to induce class switching to IgE & increase eosinophils against Helminths

Th17 - release IL17 & 22 activates neutrophils against bacteria and fungi

Th reg - down regulate immune response via FOXp3 to secrete IL10, TGF-beta and CTLA 4

23
Q

FOXp3 deficiency

A

T reg cells cannot secrete IL10 and CTLA to down regulate immune system, causing fatal autoimmune syndrome (immune dysfunction, polyendocrinopathy, enteropathy, dermatitis) which presents in first few months of life

24
Q

Co-stimulation on APC & CD4 interaction

A

B7 on APC binds CD28 to cause CD4 proliferation
B7 on APC binds CTLA to cause CD4 inactivation

25
Coeliac immunological process
Gluten -> deaminated gliadin forms Ag on HLA DQ2 or 8 on CD4 Y cells -> differentiate into Th1 cells and increase production of Anti-deamidated Gliadin IgG, Anti-tissue transglutaminase IgA (Check total IgA levels to exclude false negatives) , Anti-endomysial Ab IgG
26
IPEX
Due to mutation in FOXp3 causing decreased turnover of Treg activity - - Immune dysfunction with candida due to lack of IL17 - Polyendocrinopathy due to autoimmunity with lack of T cell inhibition in periphery - Enteropathy - X linked
27
Toll Like receptor for Gram negative bacteria
TLR 4 specific for Lipopolysacharide in gram negative cell walls
28
Hyper- IgE Syndrome
IgE > 2000 with eosinophilia "Cold" Staph infections Eczema-type rash Severe respiratory infections If autosomal dominant, can fail to lose baby teeth
29
Chronic Granulomatous Disease
- Phagocytes are unable to destroy bacteria, via respiratory burst, after ingestion - Neutrophil oxidative burst testing showing no shift - Treat with IFN-gamma which up regulates macrophages
30
Wiskott Aldrich Syndrome
"WATERS" Wiskott Aldrich Syndrome Thromboycytopenia Eczema Recurrent infections Serum IgM reduced, High IgA and IgE
31
Severe combine immunodeficiency - Types
X-linked - gamma chain deficiency Autosomal dominant - JAK 3 mutation
32
X-linked agammaglobulinaemia
Young males Due to mutation in Brutons tyrosine kinase causing absence of mature CD19 B cells and decreased immunoglobulins Asymptomatic until 6 months, when maternal IgG decreases Lymphoid hypoplasia of tonsils
33
IL1
Released by macrophages, monocytes and dendritic cells in response to PAMPs causing an inflammatory response and fever Cleavage to IL1 beta will cause hyperalgesia - blocked by colchicine and Anakinra (Rx Familial Mediterranean fever)
34
CD19, CD20, CD40
CD 19 on pro-B cells CD 20 on mature B cells CD 40 co-stimulation with MHC2 between T and B cells
35
Antibodies in compliment cascade
Classical via IgG and IgM Alternative via IgA (A for alternative)
36
Types of hypersensitivity reactions
Type 1 - IgE mediated (asthma) Type 2 - Cytotoxic - Antibody dependent (IgG) complement cascade (transfusion reaction, haemolytic anaemia) Type 3 - Immune complex (SLE, GN, RA) Type 4 - Th1, cell-mediated cytotoxic (contact dermatitis, granulomas)
37
Types of drug reactions
Immune-mediated 1. IgE mediated (immediate on second exposure I.e urticaria) 2. T cell mediated via Haptons (Delayed > 1hr i.e Steven Johnsons) Non-immune mediated 1. Direct mast cell activation i.e. Contrast, Opioids 2. COX inhibition and up regulation of Leukotrienes i.e. Samters triad with Aspirin intolerance Tryptase will be positive in any mast cell activation event I.e both IgE mediated & direct mass cell activation
38
Cytokines
IL1 - released by macrophages, monocytes and dendritic cells on PAMP binding to up regulate inflammation & fever IL2 - Th cell turnover IL6 & 8 - Acute inflammation to up regulate acute phase reactants (CRP, Mannose Binding Lectins) IL4/5/13 - Released from Th2 for IgE class-switching IFN- Gamma - Macrophage activation and IgG upregulation IL 17 & 22 - Released from Th17 against fungal infections TNF-alpha - acute inflammation (blocked by infliximab)
39
CTLA4
APC B7 binds CTLA -> deactivates T cells and downregulates immune system. CTLA antagonists -> up regulates immune system CTLA agonists -> down regulates immune system
40
CD 34
Is on stem cells only
41
MHC class expression
MHC 1 - on all nucleated cells (not on RBCs) MHC 2 - only on antigen presenting cells
42
De Georges Syndrome
“CATCH 22” Cardiac abnormalities - Tetrology of Fallot Abnormal facies Thymic aplasia Cleft Pallate Hypoparathyroidism with hypocalcaemia Deletion 22q11.2 on Chromosome 22
43
Toll Like Receptor 4
Binds to lipopolysachrides on Gram Negative bacteria
44
Types of IgA
Differ in heavy chains IgA1 - airways, serum and small intestine IgA2 - Colon and small intestine
45
Mechanism of immune tolerance
- Clonal deletion at thymus - Anergy - T reg cells
46
Tryptase
- Helpful for all mast-cell mediated reactions i.e. IgE mediated and direct mast cell activation, but will not differentiate between IgE and Non-IgE mediated mast cell activation - Peak 1-2 hours - Requires serial measurement - Less useful for food allergy
47
Late complement deficiencies
C5-9 predispose to meningococcal infection
48
B cell development
Stem cell Pro-B cell Pre-B cell - VDJ Heavy chain rearrangement Immature B cell - VJ Light chain rearrangement Naive B cell expressing IgM Mature B cell expressing IgG

RACP (17 decks)

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