immunodeficiency Flashcards
generally, T-cells deficiencies vs B cell deficiencies according to risk for infections
generally, B-cells deficiencies –> recurrent bacterial infection
generally, T-cells deficiencies –> fungal and viral infection
Immunodeficiencies are divided to
- B-cells disorders
- T-cells disorders
- B and T cell disorders
- Phagocyte dysfunction
Immunodeficiencies - B-cells disorders - types
- X-linked (Bruton) agammaglobulinemia
- Selective IgA deficiency
- Common variable immunodeficiency
X-linked (Bruton) agammaglobulinemia - defect
Defect in BTK, a tyrosine kinase gene –> no B cell maturation (X-linked recessive –> boys)
X-linked (Bruton) agammaglobulinemia - mechanism of inheritance
X-linked recessive –> boys
X-linked (Bruton) agammaglobulinemia - presentation
Recurrent bacterial and enteroviral infection after 6 months (after maternal IgG protection)
X-linked (Bruton) agammaglobulinemia - findings
- Absent B cells in peripheral blood
- Low Ig of classes
- Absent/scanty lymph nodes and tonsils
Selective IgA deficiency - defect
unknown
Selective IgA deficiency - presentation
5 As
- Majority asymptomatic
- airway and GI infections
- autoimmune diseases
- Atopy
- Anaphylaxis to IgA-containing products
Selective IgA deficiency - findings
- low IgA
2. normal IgG, IgM levels
Common variable immunodeficiency - defect
defect in B-cells differentiation (many causes)
Common variable immunodeficiency - presentation
Can be acquired in 20s-30s
- high risk of autoimmune disease
- bronchiectasis 3. lymphoma
- sinopulmonary infections
Common variable immunodeficiency - can be acquired in
20-30s
Common variable immunodeficiency - findings
- low plasma cells
2. low immunoglobulins
T-cell disorders - types
- Thymuc aplasia (DiGeorge syndrome)
- IL-12 receptor deficiency
- Autosomal dominant hyper-IgE syndrome (Job syndrome)
- Chronic mucocutaneous candidiasis
Thymuc aplasia is AKA
DiGeorge syndrome
Thymuc aplasia (DiGeorge syndrome) - defect
22q11 deletion –> failure to develop 3rd and 4th pharyngeal pouches –> absent thymus and parathyroids
Thymuc aplasia (DiGeorge syndrome) - presentation
- Tetany (hypocalcemia)
- reccurent viral/fungal infections
- conotruncal abnormalities (ef. tetralogy of Fallot, truncus arteriosus)
Thymuc aplasia (DiGeorge syndrome) - findings
- decreased T-cells
- decreased Parathormone –> decreased calcium
- absent thymic shadow on CXR
- 22q11 deletion detected by FISH
- not well developed lymph node paracortex
IL-12 receptor deficiency - defect
low Th1 response
IL-12 receptor deficiency - mode of inheritance
AR
IL-12 receptor deficiency - presentation
Disseminated mycobacterial and fungal infections
- may present after BCG vaccine administration
IL-12 receptor deficiency - may present after
BCG vaccine administration
IL-12 receptor deficiency - findings
low INF-γ
INF-γ is secreted by …. / actions
It is secreted by NK cells and T cells in response to il-12 from macrophages. actions:
- stimulates macrophages to kill phagocytosed pathogens
- Inhibits differentiation of Th2
- activates NK cells to kill virus infected-cells
- increases MHC expression and antigen presentation by all cells
Autosomal dominant hyper-IgE syndrome is also called
Job syndrome
Autosomal dominant hyper-IgE syndrome (Job syndrome) - defect / mode of inheritance
Deficiency of Th17 cells due to STAT3 mutation –> impaired recruitment of neutrophils to site of mutation
AD
Autosomal dominant hyper-IgE syndrome (Job syndrome) - presentation
FATED
- coarse Facies
- cold (noninflammed) staphylococcal Abscess
- retained primary Teeth
- IgE
- Demratoligic problems (eczema)
Autosomal dominant hyper-IgE syndrome (Job syndrome) - fingings
high IgE
low IFN-γ
Chronic mucocutaneous candidiasis - defect
T-cell dysfunction (many causes)
Chronic mucocutaneous candidiasis - presentation
Noninvasive Candida ablicans infection of skin and mucous membranes
Chronic mucocutaneous candidiasis - findings
- absent in vitro T-cell proliferation in response to Candida ablicans
- Absent cutaneous reaction to Candida ablicans
B and T cell disorders - types
- Severe combined immunodeficiency
- Ataxia-telangiectasia
- Hyper-IgM syndrome
- Wiskott-Aldrich syndrome
Severe combined immunodeficiency - defect
several types:
a. defective IL-2R gamma chain (MC, X-linked)
b. adenosine deaminase deficinecy (AR)
Severe combined immunodeficiency - presentation
- Failure to thrive
- chronic diarrhea
- thrush
- Reccurent viral, bacterial, fungal and protozoal infections
Severe combined immunodeficiency - treatment
bone marrow transplant (no concern for rejection)
Severe combined immunodeficiency - findings
- decreased T-cell receptor excision circles (TRECs)
- absence of thymic shadow on CXR
- absence of germinal centers (lymph node biopsy)
- absence of T cells (flow cytometry)
T-cell receptor excision circles (TRECs) are
small circles of DNA created in T-cells during their passage through the thymus as they rearrange their TCR genes –> indication of T-cell maturation
Ataxia-telangiectasia - defect
defects in ATM gene –> failure to repair DNA double strand breaks –> cell cycle arrest
Ataxia-telangiectasia - presentation
triad: 1. cerebellar defects (Ataxia)
2. spider angiomas (telangiectasia)
3. IgA deficiency
Ataxia-telangiectasia - findings
- increased AFP
- low IgA, IgG and IgE
- Lymphopenia
- cerebellar atrophy
- normal level of IgM
Hyper-IgM syndrome - defect
MC due to defective CD40L on Th cells --> class switching defect XR
Hyper-IgM syndrome - mode of inheritance
XR
Hyper-IgM syndrome - presentation
- severe puogenic infection early in life
2. opportunistic infection with Pneumocystis, Cryptospridium, CMV
Hyper-IgM syndrome - opportunistic infection with
- Pneumocystis
- Cryptospridium
- CMV
Hyper-IgM syndrome - findings
- normal of increased IgM
2. low IgG, IgA, IgE
Wiskott-Aldrich syndrome - defect
mutation of was gene –> T cells unable to reorganize actin cytoskeleton
XR
Wiskott-Aldrich syndrome - mode of inheritance
XR
Wiskott-Aldrich syndrome - presentation
Mneominic: WATER + autoimmune + malignancy
- Thrmobocytopenia
- Eczema
- Reccurent infections
- High risk of autoimmune disease and malignancy
Wiskott-Aldrich syndrome - findings
- low/normal IgG, IgM
- High IgE, IgA
- Fewer and smaller platelets
B and T cell disorders - types and mode of inheritance
- Severe combined immunodeficiency –> X or AR
- Ataxia-telangiectasia –> -
- Hyper-IgM syndrome –> XR
- Wiskott-Aldrich syndrome –> XR
Phagocyte dysfunction - types and mode of inheritance
- Phagocyte adhesion deficiency (type 1) –> AR
- Chediak-Higashi –> AR
- Chronic granulomatous disease –> XR
Leukocyte adhesion deficiency (type 1) - defect
defect in LFA-1 integrin (CD18) protein on phagocytes –> impaired migration and chemotaxis
AR
Leukocyte adhesion deficiency (type 1) - mode of inheritance
AR
Leukocyte adhesion deficiency (type 1) - presentation
- reccurent bacterial skin and mucosa infection
- absent pus formation
- impaired wound healing
- delayed separation of umbilical cord (>30 days)
Leukocyte adhesion deficiency (type 1) - findings
- increased neutrophils
2. no neutrophils at infection site
Chediack-Hisgashi syndrome - mechanism
Defect in lysosomal trafficking regulator gene (LYST) –> microtubule dysfunction in phagosome-lysosome fusion
AR
Chediack-Hisgashi syndrome - Mode of inheritance
AR
Chediack-Hisgashi syndrome - presentation
- reccurent pyogenic infections by staphyococci and streptococci
- partial albinism
- peripheral neuropathy
- progressive neurodegeneration
- infiltrative lymphohistiocytosis
Chediack-Hisgashi syndrome - findings
- giant granules in granulocytes and platelets
- pancytopenia
- Mild coagulation defects
Chronic granulomatous disease - mechanism
Defect of NADPH oxidase –> decreased ROS and respiratory burst in neutrophils
XR
Chronic granulomatous disease - mode of inheritance
XR
Chronic granulomatous disease - presentation
high susceptibility to CAT + organism
CAT + bugs?
CATs Need PLACESS to Belch their Hairballs
Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staphylococci, Seratia, B. cepacia, H. pylori
Chronic granulomatous disease - findings
Abnormal dihydrorhodamine (flow cytometry) test (decreased green fluorescence) Nitroblue tetrazolium dye reduction test obsolete (if + --> less blue)
MC immunodeficiency
Selective IgA deficiency
infections in immunodeficiencies (bacteria, viruses, Fungi/parasaties) - decreased T cells
bacteria: sepsis
Viruses: CMV, EBV, JCV, VZV, chronice infection with respiratory/GI viruses
fungi/paratsites: Candida (local) PCP
infections in immunodeficiencies (bacteria, viruses, Fungi/parasaties) - decreased B cells
bacteria: encapsulated
viruses: enteroviral encephalitis, poliovirus (live vaccine contraindicated)
fungi/paratsites: giardias (if no IgA)
infections in immunodeficiencies (bacteria, viruses, Fungi/parasaties) - decreased granulocytes
bacteria 1. staphylococcus 2. Burkholderia cepacia
3. Pseudomonas aeruginosa 4. Serratia 5. Nocardia
viruses: no
fungi/parasites: Candida (systemic), aspergillus, mucormycosis
infections in immunodeficiencies (bacteria, viruses, Fungi/parasaties) - low complement
bacteria –> encapsuled species with early compoment deficiencies, Neisseria with late compoment deficiencies
Immunodeficiency disorder with low INF-γ
- Il-12 deficiency
2. AD hyper-IgE syndrome (Job syndrome)
Immunodeficiency disorder with cold abscess
AD hyper-IgE syndrome (Job syndrome)
Immunodeficiency disorder with fewer and smaller platelets
Wiskott-Aldrich syndrome
Immunodeficiency disorder with delayed separation of umbilical cord
Leukocyte adhesion deficiency
Immunodeficiency disorder with infiltrative lymphohistiocytosis
Chediak-Higashi syndrome