Immunology Flashcards
Function of IL-17
induction of epithelial cells and chemokines that attract neutrophils to sites of infection and (antimicrobial) B defensins
The differentiation of CD4 T cells into TH17 cells is determined by what?
expression of transcription factor RORyT which is expressed by STAT3
Phosphorylated STAT3 dissociates from the receptor and forms homodimers that translocate the nucleus and induce expression of RORyT
Hyper IgE triad
pneumonia, recurrent staphylococcal skin abscesses, and elevated IgE
What is the mutational defect in hyperIgE
impaired TH17 differentiation
TH17 differentiation causes cells to express IL-17R to produce neutrophils, chemokines and macrophages like CXC8 which fight infection
AR IgE syndrome is associated with which gene mutation
DOCK8
AD IgE syndrome is associated with which gene mutation
STAT3
Where does the thymus derive from
The third pharyngeal pouch
Function of TBX1 gene
controls segmentation of the embryonic pharynx, growth, proper alignment and septation of the cardiac outflow tract
Where is TBX1 gene located
ch 22q11.2
heart defect, seizures, hypocalcemia and T cell lymphopenia
Digeorge syndrome
aka microdeletion of 22q11.2 region on ch. 22
Function of the AIRE gene
regulation of self recognizing T cells, therefore del. in AIRE means ++ autoimmunity
What is the ALPS mutation?
germ line mutation in TNFRSF6 (encodes Fas) which leads to increased survival of lymphocytes aka impaired apoptosis
(Autoimmunity lymphoproliferative Syndrome)
Note there are many mutations that can cause ALPS (ie. CTLA4)
What are Cryopyrinopathies aka CAPS (Cryopyrin associated periodic fever syndromes)?
Autoinflammatories spectrum of disorders including
- FCAS
- MWS
- CINCA/NOMID
Gain of function in NLRP3 gene results in hyper-activation of IL-1 beta
Occurs in an AD pattern
HIES due to germline mutations
Type 1: Jobs syndrome
Due to STAT3 gene mutation loss of function (AD)
ZNF341 gene mutation (AR)
skeletal and bone abn.
delayed shedding of primary teeth, hyperext. joints, scoliosis
Type 2: PGME mutation, DOCK8 deficiency, Tyk2 def
recurrent viral skin infections like herpes
Atopy present - food and seasonal
normal bone and teeth
HIES due to somatic mutation
STAT5b GOF mutation
presented with atopic derm, urticarial rash, resp infections, diarrhea
What is MSMD?
Mycobacteria susceptible mendelian disease
IL-12 acts on T cells –> INF gamma released
INFg acts on macrophages to attack mycobacteria
In MSMD you get neutralizing anti INF gamma autoantibodies. This neutralizes INFg and halts the pathways of IL-12
Disruption in thymus function - secondary
thymoma
What is the effects of disruption in thymus function?
can cause neutralization antibodies to Th17, IL22 and IL12/23 . Impairment in these cytokines due to auto antibodies causes problems in defence against candida
What is the effects of disruption in thymus function?
can cause neutralization antibodies to Th17, IL22 and IL12/23 . Impairment in these cytokines due to auto antibodies causes problems in defence against candida
Name PID phenocopies due to auto antibodies (4)
- AA against GM CSF –> causes pulmonary alveolar proteinosis
- AA against CI inhibitor –> Acquired angioedema
- AA against Factor H –> HUS
- AA against various cytokines, Good syndrome –> thymoma and hypogamm.
Features of ALPS (3)
with lymphadenopathy, splenomegaly, and autoimmunity.
Affected patients may also have AI hemolytic anemia, neutropenia and thrombocytopenia
They are at risk of developing lymphoma
Management of ALPS
- Immune suppression (Pred, cyclosporin A)
- for ALPS- CTLA4 –> Abatacept (CTLA4 Ig)
- Avoid splenectomy bc the risk of infections with encapsulated organisms
What is the immune defect issue in WAS
there is an inability for the T cells to reorganize their actin cytoskeleton when required which has profound effects on their function. The T cells are unable to interact with B cell and other target cells.
WAS triad
thrombocytopenia, recurrent infections, eczema
Rituxumab MOA
IgG1 CD20 specific monoclonal antibody
targets B cells from the pre- B cell stage, causing down regulation of the B cells making them less likely to be activated
Name some periodic fever syndromes associated with urticaria
- CAPS - CIAS1 associated periodic syndrome
- FCAS - fam. cold autoinflammatory syndrome
- Muckel wells
- NOMID/ CINCA
Criteria for Dupilumab therapy for atopic dermatitis
- Moderate to severe AD not adequately controlled with topical therapies, or those therapies are not advisable
- Age 6 +
Name the Major and Minor Criteria for FMF
Major:
- recurrent fevers with serositis
- AA amyloidosis without other disease
- Favourable responses to regular colchicine
Minor:
- Family history in first degree relative
- recurrent fevers
- erysipelas- erythematous rash