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37 Cards in this Set
- Front
- Back
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Three categories of immune disorders - list, define, examples
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Hypersensitivity
-exaggerated immune response; harmful to host (asthma, rhinitis, transfusion, drug reactions, transplant rejection, contact dermatitis) Autoimmunity - hypersensitivity to self antigen (type I diabetes, Hashimoto's, autoimmune hemolytic anemia, SLE, rheumatoid arthritis) Immunodeficiency - one or more aspects of immune response are absent or defective (Bruton's agammaglobulinemia, DiGeorge's, SCID, AIDS) |
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Hypersensitivity reactions
-classified by what? -type I-III -type IV |
classified by immune mechanism
I-III require specific antibody against exogenous or endogenous (autoimmune) antigen IV - cell-mediated |
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Type I Hypersensitivity
-mechanism (cells, cytokines) -histopathology -examples |
Anaphylactic - IgE binds mast cell and basophil Fc receptor --> antigen exposure --> degranulation --> histamine, serotonin, heparin, eosinophil chemotactic factor
Vascular dilation, edema, smooth muscle contraction, mucus production, inflammation Anaphylaxis, urticaria, angioedema, allergic rhinitis, asthma |
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Type II Hypersensitivity
-mechanism (cells, cytokines) -histopathology -examples |
Cytotoxic - IgG or IgM directed towards cell antigens/receptors or extracellular molecules
Cytotoxicity via two mechanisms: IgG and IgM can bind antigen on cell surface and activate complement --> lysis IgG and IgM can bind antigen --> complex bound by Fc receptors on leukocytes --> phagocytosis/lysis Cell lysis, neutrophils, macrophages, fibrinoid necrosis (IgG, complement, fibrin) Autoimmune hemolytic anemia, Goodpasture, tissue rejection, blood transfusion |
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Type III Hypersensitivity
-mechanism (cells, cytokines) -histopathology -examples |
Immune-complex mediated - antigen-antibody complexes (IgG, IgM, IgA) activate complement --> recruit neutrophils --> tissue damage
Antigens can be exogenous (viral, bacterial) or endogenous (DNA) Immune complexes can deposit generally or in particular organs Complement - C5a/C3a (chemotaxins), C3b (opsonin) Fibrinoid necrosis (necrotizing vasculitis), neutrophils, edema, microthrombi Arthus reaction, polyarteritis nodosa, serum sickness, SLE, glomerulonephritis |
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Type IV Hypersensitivity
-mechanism (cells, cytokines) -histopathology -examples |
Cell-mediated and delayed
APC w/ antigen --> CD4 and CD8 T cell activation --> Th1 cytokines (IL-12, gamma-interferon, IL-2) --> macrophages CD8 T cells - direct cell death Macrophages (epitheloid), granuloma (not always) Contact dermatitis, TB skin test, transplant rejection, type I diabetes, multiple sclerosis |
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Graft rejection - pathology
Hyperacute, acute, chronic |
Hyperacute - within mintues, type II - preformed antibodies; vasculature/endothelium
Acute - days/weeks, types II and IV Chronic - months, fibrosis/scarring due to long-term cell-mediated/antibody effects; intimal fibrosis and scarred/destroyed organ |
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Autoimmunity
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Loss of tolerance
Can have type II, III, or IV hypersensitivity Disorders can be organ specific or systemic |
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Hashimoto's (Chronic) Thyroiditis
-mechanism -histology -lab tests |
Antibodies to thyroglobulin and thyroid peroxidase; anti-TSH receptor antibodies
Clinical hypothyroidism, elevated TSH, enlarged thyroid/goiter T cell infiltrate of thyroid gland DX test - presence of anti-thyroxidase antibody |
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Grave's Disease
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Anti-TSH receptor antibodies stimulate TSH receptor --> hyperthyroidism
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Systemic Lupus Erythematosus
-mechanism -histology -lab tests |
Every organ system can be involved - depends on which autoantibodies and self-reactive T cells are present --> variable clinical presentation
Most characteristic - antinuclear antibodies - anti-double-stranded DNA antibodies (immunofluorescence) Decreased serum complement --> lots of immune complexes w/ self-antigens --> depletes complement Can get Ig and complement deposits in the skin, kidney Butterfly rash over nose/cheeks |
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Immunodeficiency - two major categories
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Primary - inherited/congenital
-genetic; mostly X-linked = mostly seen in young boys Secondary - acquired (environmental) |
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Primary immunodeficiency - subgroups
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1)B cell (antibodies)
2)T cell (virus/fungi) 3)B and T cell 4)Phagocyte |
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B cell deficiencies
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majority of primary immunodeficiencies
Increased/recurrent pyogenic infections Viruses handled normally EXCEPT enteroviruses |
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Bruton's Agammaglobulinemia
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X-linked (Xq22) --> mostly boys
Pre-B lymphocytes fail to mature Low/absent B cells, IgG, IgM, IgA Lungs, sinuses, bones |
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Isolated IgA deficiency
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Most common/mildest immunodeficiency disorder
Block in differentiation of IgA line of B cells Absent/very low IgA Upper respiratory infections, diarrhea, dermatitis |
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Hyper-IgM immunodeficiency
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X-linked; low IgG and IgA w/ normal/elevated IgM
Otitis media, pneumonia, septicemia, PCP, neutropenia, anemia, cholangitis, hepatitis, hepatoma |
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Common Variable Immunodeficiency
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2nd-3rd decade
Failure of B lymphocytes to differentiate into plasma cells Normal B cell numbers, no plasma cells; total Ig below 300 - IgG below 250 Late onset, equal sex distribution |
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DiGeorge's Syndrome
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22q11 - T lymphocyte deficiency w/ rudimentary thymus
Hypoplastic T-dependent areas in spleen, lymph nodes Normal B cell responses Recurrent viral, fungal infections Associated w/ hypoparathyroidism, cardiac abnormalities |
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Chronic Mucocutaneous Candidiasis
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Selective T cell defect - normal B cells
Recurrent candidal infections - normal antibody response Negative delayed hypersensitivity to candida antigen Intact T-cell immunity to most antigens Affects both sexes |
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Severe Combined Immunodeficiency Syndrome (SCID)
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Infections in first year of life - recurrent, persistent, severe, opportunistic - bacterial and viral
Failure to thrive, chronic diarrhea Lymphoid stem cell defect - T and B cell deficiency (both decreased or absent) Can be fatal |
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Ataxia-telangiectasis
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Autosomal recessive IgA deficiency - onset by age 2
Ataxia + telangiectasia (dilated blood vessels near skin) Recurrent sinopulmonary infections |
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Wiskott-Aldrich
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X-linked
Thrombocytopenia, eczema --> bleeding, skin rashes Risk of infection, cancer |
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Chronic Granulomatous Disease
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Disorder of WBC bactericidal function: deficient NADPH oxidase --> no activated/toxic O2 species
Early childhood - widespread granulomatous skin, lung lesions Hypergammaglobulinemia, anemia, leukocytosis |
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Chediak-Higashi
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Defect in phagolysosome
Neutropenia, defective degranulation Giant granules |
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Secondary Immunodeficiency
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Develop in person w/ previous functional immune system
Host factors - age, stress, trauma, surgery, disease states Environment factors - malnutrition, infections, drugs, radiation |
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Acquired Immune Deficiency Syndrome
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Caused by HIV - infects mainly CD4 T cells; macrophages also
Immune system becomes weakened - cannot protect against infection |
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Malnutrition-related Immunodeficiency
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World leading cause of infant and child death
Weight <80% mean - some impairment <70% mean - severe impariment Infections increase metabolic requirements --> decrease appetite --> worsen malnutrition and immunodeficiency Susceptible to respiratory infection, viral disease, gastroenteritis Primarily T-cell deficiency |
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Splenic deficiency syndromes
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Splenectomy, congenital absence, functional asplenia
Increased susceptibility to rapid overwhelming bacterial infection - H. influenzae, E. coli, pneumococci, streptococci |
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Amyloidosis - what is it?
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Systemic disease - insoluble abnormal protein deposition
Classified as beta-pleated fibrillar protein Major types - AL and AA proteins |
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Amyloidosis - distinguished by?
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1)fibrillar electron micrographic appearance
2)amorphous eosinophilic appearance (H/E stain) 3)beta-pleated sheet (x-ray diffraction) 4)apple-green birefringence (congo-red stain) 5)solubility in water and buffers of low ionic strength |
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Amyloidosis - clinical, diagnosis
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Organ deposition - kidney, spleen, liver, heart, endocrine
Diagnosis - rectal/gingival biopsy, congo red stain, serum/urine protein electrophoresis |
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AL protein
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Ig-light chain - produced by Ig-secreting cells
Deposition associated w/ monoclonal B-cell proliferation |
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AA protein
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Derived from SAA serum precursor
Seen w/ secondary amyloidosis |
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Transthyretin (TTR)
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Normal serum protein - binds and transports thyroxine, retinol
Mutations contribute to tissue depositions in the form of amyloid Found in heart deposits of aged individuals |
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B2-microglobulin
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Normal serum protein - component of MHC class I
Found in hemodialysis-complicating amyloid |
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B2-amyloid
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Core of cerebral plaques found in Alzheimers
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