Ch. 6 Disorders Of The Immune System Flashcards
(242 cards)
0
Q
Two forms of immune response?
A
Natural and acquired
0
Q
Where is IgA found?
A
Mainly in mucosal secretions (tears, nasal, resp. tract), breast milk, intestinal tract
1
Q
What does “immunity” mean?
A
From Latin term - exemption from duty
2
Q
What is natural immunity?
A
Mechanical and cellular defense mechanism
2
Q
Function of IgA?
A
Protective
3
Q
What is acquired immunity?
A
Concept of self vs non self
3
Q
Where is IgE found?
A
Trace amts in serum
4
Q
3 protective proteins in natural immunity?
A
Complement, properdin, lysozyme
4
Q
What secretes IgE?
A
sensitized plasma cells in tissue
5
Q
What is properdin ?
A
Plasma protein that activates alternative complement pway
5
Q
What are IgEs attached to?
A
Locally attached to mast cells
6
Q
What are lysozymes?
A
Low molecular weight proteins
6
Q
Function of IgE?
A
Mediates allergic rxns in tissues (hay fever, asthma) and protects against parasites
7
Q
Where are lysozymes found?
A
Tears, nasal secretions, intestinal secretions
7
Q
Where is IgD found?
A
Exclusively on B cells
8
Q
What is immunocompetence?
A
Ability to mount a response
8
Q
Function of IgD?
A
Participates in antigenic activation of B cells
9
Q
What is the body’s first line of defense?
A
Skin - mechanical and chemical barriers
9
Q
Is IgD released into serum of body fluids?
A
NO
10
Q
What is the body’s second line I defense?
A
Skin - inflammatory response, phagocytosis
10
Q
What is MHC?
A
Major histocompatibility complex
11
Q
What is the body’s third line of defense?
A
Skin - specific immune responses
11
Q
Why is MHC essential?
A
For presentation of antigens to T cells
12
Q
What are the cells of the immune system?
A
Lymphocytes, plasma cells, macrophages
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What is MHC aka?
human leukocyte antigen
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Types of lymphocytes?
T and B
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Two groups of MCH , and what are they receptors for?
Type 1 - R/Cs for CD8 Type 2 - r/cs for CD4
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Types of t lymphocytes?
```
T helper (CD4+)
T suppressor/cytotoxic (CD8+)
Natural killer (NK) cells
```
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Role of MHC in immune response?
antigen presenting cell (macrophage or B cell)
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Major lymphoid organs?
Thymus, bone marrow, lymph nodes, tonsils, spleen, Peyer's patches
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Function of MHC?
presentation of antigen to T cells
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What is Waldeyer's ring?
Lymph nodes, tonsils, adenoids
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Why are antigen presenting cells important?
T cells can only react to membrane bound antigens. W/O APCs there is NO T CELL RXN to antigens
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What does a basophil become in tissue?
Mast cell
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Where are MHC type 1 found?
On ALL NUCLEATED CELLS
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What does a monocytes become in tissue?
Macrophage
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What do MCH type 1 link APCs to?
suppressor and/or cytotoxic T lymphocytes
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What does a b lymphocyte become in tissue?
Plasma cell
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What do MCH type 2 mediate?
attachment of APC to helper T lymphocyte
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Microscopic Difference between b lymphocyte and plasma cell?
Lymphocyte = scant cytoplasm, few organelles
| Plasma cell = well developed cytoplasm and prominent rough ER
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Function of MHC type 2?
presentation of EXOGENOUS ANTIGENS that are first internalized and processed
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What is RER responsible for in plasma cells?
Production of immunoglobulins
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What are HLA subtypes used for?
Used diagnostically to identify pathologies
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Five classes of immunoglobulins?
IgG, IgM, IgA, IgE, IgD
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What is HLA type B27 used to identify?
Psoriasis, ANKYLOSING SPONDYLITIS, Inflammatory bowel disease, Reiter's syndrome (PAIR)
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What are all immunoglobulins composed of?
Light and heavy chains
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What is an epitope?
Antigenic site - can be many on an antigen
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Which chains are the same in all immunoglobulins and which are specific to each?
Light chains the same
| Heavy chains specific
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What to antibodies to SOLUBLE antigens form?
Soluble complexes that can be found in circulation
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What are the two regions on each chain of immunoglobulins?
Constant (Fc) and variable (Fab)
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What to antibodies to NON-SOLUBLE antigens form?
Bind to fixed antigens on cells - coat the cell surface
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What are the two light chains?
Kappa and lambda
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What do antigen-antibody complexes do?
Bind and activate complement
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What links immunoglobulin chains together?
Disulfide bonds between CYSTEINES
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What is complement?
Effector system -> lysis of cells, agglutination, recruitment of inflammatory cells
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What is the largest immunoglobulin?
IgM
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What is hypersensitivity rxn Type I?
Anaphylactic
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What is the function of IgM?
Neutralize microorganisms
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What is hypersensitivity rxn Type II?
cytotoxic antibody mediated
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How many complement binding sites does IgM have?
5
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What is hypersensitivity rxn Type III?
immune complex mediated
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What is the first immunoglobulin to appear on immunization or initial immune response?
IgM
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What is hypersensitivity rxn Type IV?
cell mediated - DELAYED
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What is a natural antibody against ABO blood group antigen?
IgM
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Which hypersensitivity rxns are ANTIBODY mediated?
Types I, II, and III
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What is the smallest immunoglobulin?
IgG
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Which hypersensitivity rxns are CELL mediated?
Type IV
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What is the most copious immunoglobulin?
IgG
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Mnemonic to remember hypersensitivity rxns?
ACID
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How much IgG is produced on initial immunization?
Small amounts- elevated with time
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Which Ig is Type I hypersensitivity mediated by?
IgE
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How are IgG amounts boosted?
Re-exposure to antigen
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What cell type mediates hypersensitivity rxn type I?
Mast cells or basophils
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Where can you find Fc receptors for IgG?
Macrophages, PMNs, lymphocytes, eosinophils, placenta
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Which hypersensitivity rxn has a "late-phase" response?
Type I
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What does IgG act as?
Opsonin
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How long does type I hypersensitivity rxn take and why?
After 4-6 hrs. Slow reacting substances of anaphylaxis (SRS-As)
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What is the only type of immunoglobulin to pass through placenta?
IgG
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Diseases caused by type I hypersensitivity rxns?
Hay fever (allergic rhinitis), asthma, atopic dermatitis, anaphylactic shock
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What is hay fever?
Allergic rhinitis. Typically seasonal allergy to pollen, can be due to other foreign substance
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Signs/symptoms of hay fever?
nasal itching, sneezing, nasal/conjunctival inflammation
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Tx for hay fever?
anti-histamines, vit. C, desensitization
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What is asthma?
Rxn affecting bronchi. Hypersensitivity to inhaled antigens
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Are all forms of asthma immunologically mediated?
NO
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What is asthma mediated by?
SRS-As
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Who is usually affected by asthma?
children
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signs/symptoms of asthma?
coughing and wheezing
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What mineral is indicated to relax airway muscles?
Magnesium
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What is atopic dermatitis?
Eczema
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When does atopic dermatitis usually occur?
childhood
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What percentage of all children are affected by atopic dermatitis?
10%
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What percentages of children affected w/ atopic dermatitis have family Hx?
50%
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What is genetic predisposition to atopic dermatitis associated with?
hyperproduction of IgE in response to environmental allergens
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What is the allergen that causes atopic dermatitis?
Can be anything. Inhaled, ingested in food, or direct skin contact
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What does topical corticosteroid suppression of atopic dermatitis tend to lead to?
Asthma/hay fever developing later in childhood
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What is anaphylactic shock?
Severe, systemic response to allergen
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Common causes of anaphylactic shock?
Bee sting, anesthetics (hospital), radiographic contrast (hospital)
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What is the mechanism of anaphylactic shock?
Massive release of histamine and other vasoactive substances
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Signs/symptoms of anaphylactic shock?
Choking secondary to laryngeal edema, wheezing/SOB secondary to bronchial spasm, pulmonary edema, systemic circulatory collapse d/t hypotension
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Tx for anaphylactic shock?
Epinephrine STAT, high flow O2 non-rebreather
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What causes type II hypersensitivity?
Cytotoxic antibody that reacts to antigen in cells or tissue components
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Which Ig mediates Type II hypersensitivity?
IgG or IgM
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What does activation of complement in type II hypersensitivity lead to?
Cell lysis
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Pathogenesis of type II hypersensitivity?
binding of antibody to antigen on cell surface -> complement activation -> cell lysis
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Diseases caused by type II hypersensitivity rxn?
Hemolytic anemia, goodpasture syndrome, graves disease, myasthenia gravis, idiopathic thrombocytopenic purpura, erythroblastosis fetalis, rheumatic fever, bullous pemphigoid
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What is hemolytic anemia?
Prototype type II rxn - several forms
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Forms of hemolytic anemia?
systemic autoimmune disorder (eg. SLE), foreign chemicals (drugs rxn, attachment to RBCs as haptens)
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What are the "two good pastures" affected in goodpasture syndrome?
Kidneys and lungs
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Cause of goodpasture syndrome?
Autoimmunity to component of collagen TYPE IV that has become autoallergenic
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signs/symptoms of goodpasture syndrome?
HEMOPTYSIS = most prominent. Dyspnea, cough, fatigue, fever, weight loss are common. 40% of pts have HEMATURIA
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What is seen on x-ray of pt with goodpasture syndrome?
Bilateral alveolar opacities (d/t alveolar hemorrhage)
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What causes Graves disease?
Autoantibody against thyroid r/c for TSH. Stimulatory => continuous synthesis of T3/T4 (hyperthyroid)
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Signs/symptoms of Graves disease?
EXOPHTHALMOS, goiter, muscle wasting, fine hair, sweating, tachycardia, wt. loss, oligomenorrhea, tremor
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What causes exophthalmos in Graves disease?
Igs directed to specific R/Cs in orbital fibroblasts and fat - results in release of proinflammatory cytokines, inflammation, and accumulation of glycosaminoglycans
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What is Myasthenia Gravis?
hypersensitivity type II disorder. Caused by autoantibody and Cell-mediated DESTRUCTION OF ACH RECEPTORS
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Who is most commonly affected by myasthenia gravis?
young women
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What makes symptoms of myasthenia gravis better/worse?
Worsen with muscle activity, improve with rest
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How is myasthenia gravis diagnosed?
antibody testing to Ach r/c, electromyography, IV edrophonium challenge
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Signs/symptoms of myasthenia gravis?
Most common = ptosis, diplopia, muscle weakness after using affected muscle, proximal limb weakness
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What percentage of myasthenia gravis pts have affected ocular muscles?
Initially 40%, eventually 85%
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What happens to hand grip in myasthenia gravis?
Alternates between weak and normal (milkmaid's grip)
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What happens to neck muscles in myasthenia gravis?
may become weak
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When does generalized myasthenia develop in MG pts?
Usually w/in first 3 yrs
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What happens to sensation and DTRs in MG pts?
NORMAL
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What is a type III hypersensitivity rxn due to?
acute inflammation in response to circulating antigen-antibody immune complexes deposited in vessels or tissues
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What do ag-ab complexes do in type III hypersensitivity rxns?
Can activate complement system OR bind to/activate certain immune cells => release of inflammatory mediators
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What do the consequences of immune complex formation depend on in type III rxns?
Relative proportions of antigen and antibody in immune complex
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Progression of type III hypersensitivity rxns?
Early - excess antigen, small ag-ab complexes which DO NOT activate complement. Later (antigen/antibody more balanced) - larger immune complexes, deposited in various tissues causing systemic rxns
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Diseases cause by type III hypersensitivity rxns?
Serum sickness, poststreptococcal glomerulonephritis, arthus rxn, polyarteritis nodosa, systemic lupus erythematosus, rheumatoid arthritis, hypersensitivity pneumonitis
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What is poststreptococcal glomerulonephritis?
Type III rxn, usually follows upper respiratory tract infection by nephritogenic streptococcal strain
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Pathogenesis of poststreptococcal glomerulonephritis?
Antigen "planted" onto glomerular basement membrane during filtration -> complement inflammation evoked
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What is the Arthus rxn?
immune-complex mediated rxn, involves deposition of ag-ab complexes mainly in the vascular walls, serosa, and glomeruli
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According to CDC, how often are Arthus rxns reported after vaccinations?
RARELY
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Which vaccines can cause Arthus rxns?
TETANUS toxoid-containing or DIPHTHERIA toxoid-containing
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What is the antigen for polyarteritis nodosa in Arthus rxn?
UNKNOWN
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Early stages of Arthus rxn?
focal fibrinoid necrosis, acute inflammation
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Chronic stages of Arthus rxn?
wall destruction, microaneurysms, thrombosis, occlusion/infarct
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Why is "nodosa" part of the name in Arthus rxn (polyarteritis nodosa)?
Because of fibrous nodules along medium size arteries that are affected (nodosa = knotty)
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What is seen histologically in glomerulonephritis associated with SLE?
deposition of complement-activating immune complexes - IgG, and consequent infiltration by inflammatory cells
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What are type IV hypersensitivity rxn?
DELAYED hypersensitivity - T cell mediated
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Four subtypes of type IV hypersensitivity rxn, and cells involved?
Iva = Type 1 helper T cells, IVb = type 2 helper T cells, IVc = cytotoxic T cells, IVd = IL-8-secreting T cells
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How are T cells activated (type IV hypersensitivity)?
sensitized after contact w/ a specific antigen, activated by REEXPOSURE to same antigen
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How do T cells damage tissue (type IV hypersensitivity)?
by direct toxic effects OR through release of cytokines
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Diseases caused by type IV hypersensitivity rxns?
Contact dermatitis (NO GRANULOMA), chronic transplant rejection, graft-vs-host dz, tuberculosis, leprosi, fungal infections, rxn to tumors, sarcoidosis, Type I DM, MS, Guillain-Barre syndrome, Hashimotos thyroiditis, PPD
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What is type I DM theorized to be?
virally triggered autoimmune response (immune system attacks virus infected cells as well as Beta cells in pancreas)
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What virus is implicated in type I DM?
Coxsackie virus family (German measles)
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Types of transplantation? (4)
1. autograft (self) 2. isograft/synergeneic graft (identical twin or clone) 3. homograft/allograft (w/in species) 4. xenograft
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What should be tested for before allografting?
histocompatibility using HLA antigens
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Types of transplant rejection? (3)
1. hyperacute reaction 2. acute reaction 3. chronic rejection
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What happens in chronic transplant rejection?
obliteration of arterial lumen
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What determines the outcome of transfusion?
Major blood types (ABO system)
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What agglutinin does Type A blood have?
B agglutinin
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What agglutinin does type B blood have?
A agglutinin
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What agglutinin does type AB blood have?
NONE
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What agglutinin does type O blood have?
BOTH A and B agglutinin
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Which blood types can type A GIVE to?
A, AB
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Which blood types can type A RECEIVE from?
A, O
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Which blood types can type B GIVE to?
B, AB
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Which blood types can type B RECEIVE from?
B, O
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Which blood types can type AB GIVE to?
AB
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Which blood types can type AB RECEIVE from?
AB, A, B, O *UNIVERSAL ACCEPTOR*
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Which blood types can type O GIVE to?
O, AB, A, B *UNIVERSAL DONOR*
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Which blood types can type O RECEIVE from?
O
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What happens if type A is given to a person who is type B?
HEMOLYSIS
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What happens if type B is given to a person who is type A?
HEMOLYSIS
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What happens if type A is given to a person who is type AB?
NO REACTION - Acid and water rxn rule
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What happens if type AB is given to a person who is type A?
HEMOLYSIS
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What happens if type A is given to a person who is type O?
HEMOLYSIS
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What happens if type O is given to a person who is type A?
NO REACTION
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What is Rh factor?
(+) or (-) charge on blood cells
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What happens if Rh- mother has Rh+ fetus? (first pregnancy)
Nothing
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What happens if Rh- mother has Rh+ fetus? (SECOND pregnancy)
Mother is sensitized to Rh+, => anti-Rh cells cause erythroblastosis fetalis in fetus
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What should be given to an Rh- w/in 12 hrs postpartum?
RhoGAM - binds blood from fetus before immune system sensitized
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Clinical features of Rh factor incompatibility?
1. Hydrops fetalis 2. Erythoroblastosis fetalis 3. Icterus gravis neonatorum
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If mother is Rh- and fetus is Rh+, what must father be?
Rh+
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What is icterus gravis neonatorum?
jaundice of basal ganglia of brain
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What is autoimmune disease?
abnormal response to self-antigens
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How do you make diagnosis of autoimmune disease?
look for: 1. autoantibodies 2. immune mechanisms 3. indirect evidence (ex. If steroids help)
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What causes autoimmune diseases?
Familial - genetic predisposition. Certain HLA-haplotypes more often linked to autoimmune diseases
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Which sex is more commonly affected by autoimmune diseases?
Women
141
Types of autoimmune diseases? (2)
1. systemic 2. single organ
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Examples of systemic autoimmune diseases?
SLE, rheumatic fever, rheumatoid arthritis, systemic sclerosis, polyarteritis nodosa
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Examples of single organ autoimmune diseases?
MS (CNS), Hashimotos thyroiditis/Graves disease (thyroid), autoimmune hemolytic anemia (blood), pemphigus vulgaris (skin), myasthenia gravis (muscle)
144
What percentage of SLE pts have ANA?
Virtually all
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What percentage of SLE pts have kidney involvement?
75%
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Characteristic sign of SLE?
Butterfly rash
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When does first episode of acute rheumatic fever (ARF) most often occur?
Between 5 and 15 yrs - UNCOMMON before 3 or after 21
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How do you test for rheumatic fever prevention?
test for group A streptococcal (GAS) infection in pt with pharyngitis
149
What is the incidence of rheumatic fever in the US?
<1/100,000
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When do higher attack rates of ARF occur?
with certain streptococcal M protein serotypes and STRONGER HOST IMMUNE RESPONSE
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Etiology of ARF?
GAS infection (host and environmental factors also important)
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What do GAS M proteins share epitopes with?
Proteins in synovium, heart muscle, and heart valve
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What is most often affected in rheumatic fever?
joints, heart, skin, CNS
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What is rheumatoid arthritis (RA)?
SYMMETRICALLY inflamed peripheral joints
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Which sex is more commonly affected by RA?
Women 2-3x more likely to be affected
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Pathophysiology of RA?
immunologic abnormalities (type III hypersensitivity). Plasma cells produce RHEUMATOID FACTOR antibodies
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Signs/symptoms of RA?
begins w/ systemic and joint systems - early morning stiffness, fatigue, malaise, anorexia, generalized weakness. Joints painful, swollen, stiff
158
How do you differentiate RA from osteoarthritis?
RA is characteristically SYMMETRIC
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How long does morning stiffness typically last in RA pts?
>60 min
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Types of immunodeficiency diseases? (2)
Primary (congenital) and Secondary (acquired)
161
Primary immunodeficiency diseases? (3)
1. Severe combined immunodeficiency 2. Isolated deficiency of IgA 3. DiGeorge's syndrome
162
What is severe combined immunodeficiency?
defect of lymphoid stem cells - Pre-B, pre-T cells
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What is the most common PRIMARY immunodeficiency disease?
Isolated deficiency of IgA (1:700)
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Which primary immunodeficiency disease is often asymptomatic?
Isolated deficiency of IgA
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What is DiGeorge's syndrome?
T cell deficiency related to aplasia of thymus
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What is AIDS?
Acquired Immunodeficiency Syndrome
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What causes AIDS?
Human immunodeficiency virus (HIV) - RNA retrovirus
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What does HIV do?
infects T HELPER CELLS (CD4)
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Where is HIV stored in the body?
In macrophages and related phagocytic cells
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Clinical presentation of HIV/AIDS?
Acute illness, asymptomatic infection, persistent generalized lympadenopathy
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What is the terminal phase of HIV?
AIDS
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Pathologic findings of CNS in AIDS?
meningitis, encephalitis, dementia
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Pathologic findings of Mouth in AIDS?
Herpes labialis, THRUSH
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Pathologic findings of lung in AIDS?
pneumonia
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Pathologic findings of small intestine in AIDS?
malabsorption
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Pathologic findings of large intestine in AIDS?
colitis, proctitis
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Pathologic findings of skin in AIDS?
KAPOSI'S SARCOMA, dermatitis, folliculitis, impetigo
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Pathologic findings of lymph nodes in AIDS?
lymphadenopathy
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Pathologic findings of tumors in AIDS?
lymphoma
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Opportunistic infections in lung in AIDS?
pneumocystitis carinii, aspergillus fumigatus, Candida albicans pneumonia
181
Opportunistic infections in GI in AIDS?
Candida albicans, herpes or CMV, stomatitis, esophagitis, mycobacterium avium-intracellulare, cryptosporidium enteritis, fungal or bacterial proctitis
182
Opportunistic infections in CNS in AIDS?
toxoplasma gondii encephalitis, cryptococcus neoformatns meningitis
183
Tumors that develop in AIDS? (3)
Lymphoma of lymph nodes or GI tract, lymphoma of CNS, Kaposi's Sarcoma
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4 types of immune deficiencies?
1. decreased production 2. decreased activation 3. phagocytic cell deficiency 4. idiopathic dysfunction
185
3 types of decreased production that cause immune deficiency?
1. B cells 2. T cells 3. B AND T cells
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What does decreased production of B cells cause?
Brutons agammaglobulinemia
187
What is brutons agammaglobulinemia associated with?
Recurrent bacterial infections
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Which sex is affected by Brutons agammaglobulinemia?
Boys (X LINKED)
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What is caused by decreased production of T cells?
Thymic aplasia - DiGeorge syndrome
190
What does DiGeorge syndrome present with?
Tetany owing to hypocalcemia
191
What is caused by deficiency of B AND T cells?
severe combined immunodeficiency (SCID)
192
4 types of decreased activation that cause immune deficiencies?
1. T Cells - IL12 r/c deficiency 2. B cells - hyper-IgM syndrome 3. B cells - Wiskott-Aldrich syndrome 4. Macrophages - Job's syndrome
193
What is Wiskott-Aldrich syndrome?
X linked defect in ability to mount IgM response to bacteria
194
What is Wiskott-Aldrich syndrome associated with?
elevated IgA levels
195
Triad of symptoms of Wiskott-Aldrich syndrome?
recurrent pyogenic infections, thrombocytopenic purpura, eczema
196
What is Job's syndrome?
failure of IFN-gamma production by helper T cells
197
3 types of phagocytic cell deficiencies that cause immune deficiencies?
1. Leukocyte adhesion deficiency syndrome (type 1) 2. Chediak-Higashi disease 3. Chronic granulmoatous disease
198
4 idiopathic dysfunction that cause immune deficiencies?
1. T cells - chronic mucocutaneous candidiasis 2. B cells - selective immunoglobulin deficiency 3. B cells - ataxia-telangiectasia 4. B cells - common variable immunodeficiency
199
What is amyloid?
Inert extracellular material defined in terms of its PHYSICAL properties (NOT biochemical)
200
Physical properties of amyloid?
Fibers 7.5 nm thick (electron microscopy), stains with Congo red (appears green under polarized light), Beta-pleated sheet (radiographic crstallography)
201
Biochemical types of amyloid?
AA amyloid, AL amyloid, many other forms
202
Clinical presentation of amyloid deposition? (2)
1. systemic amyloidosis (deposition of amyloid in various organs) 2. localized organ-specific amyloid deposits (ex. Alzheimers dz in brain)
