Immune deficiencies Flashcards
X-linked (Bruton’s) agammaglobulinemia
Defect: x-linked recessive (increased in boys) defect in BTK a tyrosine kinase gene (no B cell maturation)
Presentation: recurrent bacterial infections after 6 mo (decreased maternal IgG) as a result of opsonization defect
Findings: normal pro-B, decreased maturation, decreased number of B cells, decreased immunoglobulins of all classes
Selective IgA deficiency
Defect: unknown, most common immunodeficiency
Presentation: majority a symptomatic. Can see sinopulmonary infections, GI infections, autoimmune disease. Anaphylaxis to IgA containing blood products
Findings: IgA < 7 mg/dl with normal IgG, IgM, and IgG vaccine tigers. False positive b-hCG tests due to presence of heterophile antibody
Common variable immunodeficiency (CVID)
Defect in b-cell maturation (many causes)
Can be acquired in 20s-30s: increased risk of autoimmune disease, lymphoma, sinopulmonary infections
Normal number of B cells; decreased plasma cells, immunoglobulin (low serum IgG)
Thymic aplasia (DiGeorge syndrome)
22q11 deletion; failure to develop 3rd and 4th pharyngeal pouches
Tetany (hypocalcemia), recurrent viral/fungal infections (T-cell deficiency), congenital heart and great vessel defects
Thymus and parathyroids fail to develop: leading to decreased T cells, decreased PTH, decreased calcium; absent thymic shadow on CXR
IL-12 receptor deficiency
Decreased Th1 response
Disseminated mycobacterial infections
Decreased IFngamma
Hyper-IgE syndrome
Th1 cells fail to produce IFNgamma leading to inability of neutrophils to respond to chemo tactic stimuli
FATED: course Facies, cold (non inflamed) staph Abscesses, retained primary Teeth, increased IgE, Derrmatologic problems (eczema)
Increased IgE
Chronic mucocutaneous candiasis
T cell dysfunction
Candida albicans infections of skin and mucous membranes
Severe combined immunodeficiency
Several types: defective IL-2 receptor (most common x-linked), adenosine deaminase deficiency
Failure to thrive, chronic diarrhea, thrush. Recurrent bacterial, viral, fungal infections. Absence of thymic shadow, germinal centers on lymph node biopsy and B cells on peripheral blood smear
Treatment: bone marrow transplant (no allograft rejection)
Findings: decreased T cell recombinant excision circles (TRECs)
Ataxia-telangiectasia
Defects in ATM gene, which codes for DNA repair enzymes
Cerebellar defects (ataxia), spider angioma (telangiectasia), IgA deficiency
Increased AFP
Hyper IgM syndrome
Most commonly defective CD40L on helper T cells = inability to class switch
Severe pyogenic infections early in life
Increased IgM, severely decreased other classes
Wiskott-Aldrich syndrome
X-linked in WAS gene on X chromosome: T cells unable to reorganize actin cytoskeleton
Thrombocytopenic purpura
Infections
Eczema
Increased IgE, IgA; decreased IgM
Thrombocytopenia
Leukocyte adhesion deficiency (type I)
Defect in LFA-1 integrin (CD18) protein on phagocytes
Recurrent bacterial infections, absent pus formation, delayed separation of umbilical cord
Neutrophilia
Chediak-Higashi syndrome
Autosomal recessive; defect in lysosomal trafficking regulator gene (LYST). Micro tubule dysfunction in phagosome lysosome function
Recurrent pyogenic infections by staph and strep; partial albinism, peripheral neuropathy
Giant granules in neutrophils
Chronic granulomatous disease
Lack of NADPH oxidase: decreased reactive oxygen species and absent respiratory burst in neutrophils
Increased susceptibility to catalase-positive organisms
Abnormal DHR flow cytometry test. Nitro blue tetrazolium dye reduction test no longer preferred
