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Flashcards in Immunodeficiency Deck (20)

Children have recurrent infections

-toddlers have ~6 respiratory per year
-daycare attendees average 9
-children exposed to second hand smoke average 12
-symptoms from a common cold last for 4-12 days (mean 6.8 days)


When should an immune evaluation be considered

-two or more invasive bacterial infections is unusual
-persistent or recurrent sinopulmonary infections warrant further evaluation
-unusual etiologic agents or unsual severity of an otherwise common infection may be a red flag


Evaluation for immunodeficiency

-physical exam


History of children with immunodeficiency

-growth and development
-types and sites of infections
-severity of infections, complications
-specific organisms
-HIV risk factors
-diarrhea, malabsorption
-autoimmune or allergic phenomenon
-family history- any unexplained earl infant deaths


Physical Exam with immunodeficiency

-physical and anatomic barriers
-growth and development
-tonsils, nodes, liver and spleen
-rash: eczyma, seborrhea, petechiae, others


Nonimmunologic lines of defense

-skin and mucous membranes- eczyma, burns, open fractures, sinus tracts
-adequate drainage of body fluids- eustation tube dysfunction, ciliary immotility, cystic fibrosis, ureteral reflux
-foreign bodies- medical, accidental


Four limbs of the immune system

-Cellular immunity- T-cells, NK-cells, cytokines-7%
-Humoral immunity- B- cells, immunologlobulins-46%
-Combined- 25%


Severe Combined Immunodeficiency: SCID

-6 week old, failure to thrive, oral thrush, skin rash, diarrhea
-75% patients are male
-X linked and autosomal recessive
-early death without bone marrow transplant
-IL-2 gamma chain defect
-Adenosine deaminase (ADA) deficency)
-Purine nucleotide phosphorylase deficiency
-T Cell signal transduction defects


Beta chain

-this is often the defect with SCIDS
-problems with IL-21 (B cell maturation_
-Il-15- NK cell development
-IL-9- hematopoiesis
-IL-7- T cell development
-IL-4- class switch recombination
-IL-2 peripheral T cell homeostasis


SCIDs Labs

-enumeration of specific lymphocytes subsets assists in diagnosis
-analysis of lymphocyte proliferation in response to
1- Mitogens (PHA, concanavalin A, pokeweed)
2- Non-self HLA antigens in a mixed lymphocyte culture
3- Specific antigens


Treatment for SCIDs

-immediate bone marrow transplant
-risks include invasive, life threatening viral, fingal, and bacterial infections
-thrush is commno
-aggressive treatment with antibiotics, replacement immunoglobulin, and often antivirals and antifungals while awaiting transplant


Humoral Immunodeficiency

-present with pneumonia, bronchiectasis (thickening and scarring), chronic problems with sinusitis
-have to rule out cystic fibrosis, immotile cilia syndrome and HIV
-B cell enumeration (C19 and/or CD20)
-Quantitative immunoglobins- IgG, A and M, consider IgG subclasses, pre and post vaccine titers, isohemmagglutins


Types of Humoral Immunodeficiency

-X-linked Agammaglobulinemia- absence of B cells due to mutation in Bruton's tyrosine kinase (BTK)
-CD40 ligand deficiency- hypogammaglobulinema with hyper-IgM
-common variable immunodefiency
-selective defect in anti-polysaccharide antibody production
-TH1 cell -> opportunistic infections because macrophages aren't properly being active
-infectious risk include encapsulated bacterial pathogens, especially Strep pneumoniae
-unique susceptibility to chronic enterovirus meningoencephalitis
-autoimmune disease common
-lifelong risk of lymphoma


Medical Management of Humoral Immunodeficiency

-immunoglobulin replacement, usually monthly
-early identification and treatment of infections,including enteroviral disease
-aggressive pulmonary follow-up


Selective IgA deficiency

-incidence 1:600
-2/3 are asymptomatic
-can be associated with IgG subclass 2 deficiency
-recurrent sinopulmonary infections
-defect in producing antibodies to polysaccharide antigens


Complement Deficiency

-Neisseria like meningococcemia or gonorrhea
-IV antibiotics
-receive meningococcal vaccine and antibiotic prophylaxis


Phagocyte deficiency

-present with liver abscess from Staph aureus, past history of pulmonary aspergillous (weird stuff)
-common neutrophil defect= chronic granulomatous disease
-low activity of NADPH oxidase
-highest risk with catalase positive bacteria
-develop fungal infections- aspergillus or pseudallescheria
-treatment: antibiotic prophylaxis, early identification and treatment of infections, interferon gamma
-Other disorders- B integrin CD11/CD18 or selectin deficiency, Chediak-Higashi or Job's syndrome


Cellular Immunodeficiency

DiGeorge syndrome- abnormal embryonic development of the 3rd and 4th pharyngeal pouches
-congenital thymic hypoplasia/aplasia-variable T cell numbers and function
-congenital heart disease (LV outflow tract)
-infection risks include invasive and severe viral and fungal disease
-thymic transplants for severe immunodeficiency
-irradiated blood products only
-many patients have gradual improvement in cellular immune function over time



-caused by a virus HIV
-loss of CD4+ T cells
-opportunistic infections
-associated with certain malignancies- Kaposi's sarcoma, lymphoma and squamous cell carcinoma


Opportunistic infections from HIV

-Bacterial-Tuberculosis, Mycobacterium Avian Complex
-Fungal- PCP, candidiasis, cryptococcosis and penicilliosis
-Protozoal-toxoplasmosis, microsporidiosis, cryptosporidiosis, isopsoriases, and leishmaniasis
-Viral- CMV, herpes simplex, herpes zoster virus