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39 Cards in this Set
- Front
- Back
disorders manifesting as defects in both B and T cell arms of adaptive immunity are classified as
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severe combined immunodeficiency (SCID)
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Breakdown of SCID causes
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50% X-linked; autosomal; half of autosomal and X-linked causes unknown
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what mutation causes half X-linked SCID cases
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cytokine receptor subunit gamma
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what normally signals via this X-linked mutation
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IL-2, IL-4, IL-7, IL-9, and IL-15
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IL-7 fxn
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immature T cell proliferation
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IL-15 fxn
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major cytokine involved in NK cell proliferation and maturation
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what causes half autosomal SCID cases
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mutation in adenosine deaminase (ADA)-involved in breakdown of purines
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what occurs with ADA mutation
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accumulation of toxic purine metabolites in cells that are actively synthesizing DNA
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other cause of autosomal SCID
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mutation in kinase involved in signaling by the gammac cytokine receptor chain (similar to X-linked); rare cases due to mutation in RAG1 or 2 gene
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what is fxn of RAG1 and 2
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encode lymphocyte specific components of VDJ recombinase-required for Ig and T cell receptor gene recombinations and lymphocyte maturation
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most common clinical syndrome caused by block in B cell maturation
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X-linked agammaglobulinemia
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what causes decrease/absence of mature B cells in agammaglobulinemia
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mutation in kinase called B cell tyrosine kinase or Bruton tyrosine kinase (Btk)
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Btk fxn
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activated by pre-B cell receptor and delivers biochem signals that promote maturation
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DiGeorge syndrome
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incomplete dvlp of thymus (and parathyroids) and failure of T cell maturation
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X-linked hyper-IgM syndrome
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defective B cell heavy chain isotype switching, so IgM is major serum antibody; severe deficiency against intracellular microbes with cell-mediated immunity
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what causes X-linked hyper-IgM
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mutation in CD40 ligand; leads to defective T cell-dependent B cell responses and T cell-dependent macrophage activation in cell-mediated immunity
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common variable immunodeficiency
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group of disorders characterized by poor antibody responses to infections and reduced serum levels of IgG, IgA, and often IgM
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bare lymphocyte syndrome
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failure to express class II MHC molecules due to mutations in transcription factors that enduce MHC II expression
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class II MHC fxn
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display peptide antigens for recognition by CD4+ T cells; critical for maturation and activation of T cells
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Chronic granulomatous disease
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mutations in enzyme phagocyte oxidase-unable to kill phagocytized microbes
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phagocyte oxidase fxn
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catalyzes production of microbicidal ROS in lysosomes
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Leukocyte adhesion deficiency
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mutation in integrins or enzymes required for expression of ligands for selectins; leukocytes not recruited normally to sites of infection
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C3 deficiency causes
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severe infections and usually is fatal
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C2 and C4 deficiency
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components of classical pathway-immune complex mediated disease resembling lupus
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why does C2 and C4 lead to lupus like disease when absent
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classical pathway is involved in removal of immune complexes that are constantly being formed during humoral responses
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Chediak-Higashi syndrome
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immunodeficiency in which lysosomal granules of leukocytes do not form normally
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Wiskott-Aldrich syndrome
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eczema, reduced blood platelets, and immunodeficiency; X-linked
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mutation in Wiskott-Aldrich syndrome
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protein that binds various adapter molecules and cytoskeletal components in hematopoietic cells
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Ataxia-telangiectasia
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gait abnormalities, vascular malformations (telangietasia), and immunodeficiency; mutation in DNA repair gene
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why does ataxia-telangiectasia result in immunodeficiency
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during recombination of antigen receptor gene segments-results in defective lymphocyte maturation
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Protein-calorie malnutrition and immune fxn
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deficiencies in virtually all components of immune system
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components of infectious HIV particle
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2 RNA strands within protein core, surrounded by lipid envelope derived from infected host cell (but containing viral proteins)
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how does HIV infect cells
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mainly via gp120-major envelope glycoprotein; binds CXCR4 and/or CCR5 of CD4 cells
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provirus
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integrated viral DNA
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what may account for loss of T cells exceeding HIV infected T cells
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T cells chronically activated -eventual apoptosis via cativation-induced cell death
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what occurs during clinical latency of HIV infected person
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usually progressive loss of CD4+ T cells in lymphoid tissues and destruction of architecture of lymphoid tissues
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normal CD4+ level and level of AIDS
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1500 cells/mm^3 vs 200
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why are CD8+ CLT fxn lowered in AIDS
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CD4+ required for full responses to many viral antigens
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two most common cancers assocaited with AIDS
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B cell lymphoma (EBV) and Kaposi sarcoma (herpesvirus)
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