Hypersensitivity Flashcards
What bacteria are associated with CRP?
Pneumococcus spp.
What type of biomolecule is CRP?
Protein
In which regions of the electrophoretic pattern does CRP appear?
β region
γ region
What is CRP classified as in the context of immune response?
Acute Phase Reactant
What are the possible results for a CRP test?
Positive (+)
Negative (-)
What conditions can a positive CRP result indicate?
CRP infection
What is a common protein that is often analyzed alongside CRP?
Albumin
What is the role of CRP as a marker in the body?
Nonspecific marker for infection
How sensitive is CRP as an inflammatory marker?
Very Sensitive but Non-specific
What other test is often used in hematology for inflammation assessment besides CRP?
ESR (Erythrocyte Sedimentation Rate)
What is the definition of hypersensitivity?
Exaggerated or uncontrolled immune response to an antigen
Causes inflammation, cell destruction, or tissue injury
How is hypersensitivity classified?
Based on time after exposure to antigen
What are the types of hypersensitivity?
Immediate hypersensitivity: antibody mediated
Delayed hypersensitivity: cell mediated
What was the original meaning of allergy?
Altered reaction to external substances
Atopy: immediate hypersensitivity by IgE antibodies
What are the properties of IgE antibodies?
Specific for various allergens
What are some common allergens?
Animal dander
Pollens
Foods
etc.
Which types of hypersensitivity reactions are antibody dependent?
Types I, II, III
Which type of hypersensitivity reaction is cell mediated?
Type IV
What is a common characteristic among different types of hypersensitivity reactions?
Overlapping symptoms among types
What type of reaction is involved in Type I hypersensitivity?
Immediate reaction
What severe reaction can Type I hypersensitivity cause?
Anaphylaxis
What is the time lag for Type I hypersensitivity reactions?
Short time lag (seconds to minutes)
Which antibody is the key reactant in Type I hypersensitivity?
IgE
What types of antigens trigger IgE in Type I hypersensitivity?
Atopic antigens or allergens
What does the Skin Puncture Test (SPT) for Type I hypersensitivity involve?
Series of scratches or needle pricks
What indicates a positive reaction in the Skin Puncture Test (SPT) for Type I hypersensitivity?
Red, raised, itchy area
What does a positive reaction in the Skin Puncture Test (SPT) indicate?
Allergy to specific allergen
What does the Radioimmunosorbent Test (RIST) use?
Radiolabeled IgE
In RIST, what does the patient’s IgE compete with?
Radiolabeled IgE for binding sites
What is the solid phase in RIST coated with?
Anti-IgE
Why has RIST been largely replaced by other methods?
Expense and difficulty of working with radioactivity
What was the original commercial testing method for specific IgE?
Radioallergosorbent Test (RAST)
What is the purpose of RAST?
Allergen-specific IgE detection
What do newer methods of specific IgE testing use instead of radioactive labels?
Enzyme or fluorescent labels
What radioactive labelled test measures total IgE level?
Radioimmunosorbent Test (RIST)
What radioactive labelled test measures specific IgE level?
Radioallergosorbent Test (RAST)
What are the key reactants involved in Type II hypersensitivity?
IgG
IgM
Where are the antigens located in Type II hypersensitivity?
Cell surface antigens
What can cell surface antigens be in Type II hypersensitivity?
Altered self-antigens
Heteroantigens
Type II hypersensitivity also known as?
Cytotoxic hypersensitivity
What process involves antibody coating cellular surfaces in Type II hypersensitivity?
Opsonization
What immune system component is activated in Type II hypersensitivity?
Complement cascade
What is an example of a Type II hypersensitivity reaction?
Transfusion reactions
What is another name for the Coombs Test?
Antiglobulin test
What does the Coombs Test check for?
Antibodies causing red blood cells to die early
Who discovered the Coombs Test?
Coombs, Mourant, Race
What is the Coombs reagent made of?
Antihuman globulin
How is the Coombs reagent produced?
By injecting human globulin into animals
What happens to red cells with complement or IgG antibodies in the Coombs Test?
They don’t agglutinate directly
What is necessary for agglutination in the Coombs Test?
Additional antibody needed for agglutination
What role does the additional antibody play in the Coombs Test?
Forms a “bridge” causing agglutination
What is another name for Direct Antiglobulin Testing (DAT)?
Direct Coombs test
What does the Direct Antiglobulin Test (DAT) detect?
Antibodies (IgG or C3) on red blood cells
What conditions can the DAT help diagnose?
Hemolytic anemia
Jaundice in newborns
What does agglutination of RBCs indicate in the DAT?
Positive test
What conditions can be detected using DAT?
Rh incompatibility
ABO incompatibility
What is another name for the Indirect Coombs Test?
Indirect Antiglobulin Test (IAT)
What does the Indirect Coombs Test look for?
Free-flowing antibodies against certain red blood cells
What is the primary purpose of the Indirect Coombs Test?
To determine if you may have a reaction to a blood transfusion
How is the Indirect Coombs Test used in prenatal labs?
As an “antibody screen” to identify minor antigens
What is obtained from the recipient in the first step of the Indirect Coombs Test?
Serum containing antibodies (Ig’s)
What is added to the recipient’s serum in the Indirect Coombs Test?
Donor’s blood sample
What forms as a result of the recipient’s antibodies targeting the donor’s red blood cells?
Antibody-antigen complexes
What is added to the solution in the Indirect Coombs Test to cause agglutination?
Anti-human Ig’s (Coombs’ antibodies)
What indicates a positive test result in the Indirect Coombs Test?
Agglutination of red blood cells
What type of hemolysis occurs in the Reticuloendothelial System (RES) involving IgG?
Extravascular hemolysis
What type of hemolysis occurs in blood vessels involving IgM?
Intravascular hemolysis
What type of hypersensitivity is Type III hypersensitivity?
Immune complex-mediated
What antibodies are involved in Type III hypersensitivity reactions?
IgG or IgM
What mediates destruction in Type III hypersensitivity?
Complement
What type of antigen is involved in Type III hypersensitivity diseases?
Soluble antigen
What forms when soluble antigens combine with antibodies in Type III hypersensitivity?
Immune complexes
What disease that is associated with Type III hypersensitivity?
Systemic Lupus Erythematosus (SLE)
What test is used to detect antibodies in Type III hypersensitivity?
Agglutination reactions
What type of particles are used in agglutination reactions for Type III hypersensitivity?
Antigen-coated carrier particles (e.g., red blood cells or latex particles)
What is another method used to test for Type III hypersensitivity besides agglutination?
Enzyme immunoassays
What staining technique is used to determine immune complex deposition in tissues?
Fluorescent staining of tissue sections
What pathogen is associated with the Francis Skin Test?
Streptococcus pneumoniae
Why is the Mantoux & Vollmer’s Patch Test performed?
To diagnose Tuberculosis
What pathogen is detected by the Frei Test?
Chlamydia pathogens (Bedsonia)
How does the Schick Test identify an infection?
By detecting Corynebacterium diphtheriae
What disease is diagnosed using the Dick’s Test?
Erysipelothrix
What condition is identified with the Lepromin Test?
Leprosy
What type of disorder is associated with Type III hypersensitivity?
Autoimmune disorder
What forms in Type III hypersensitivity reactions?
Antigen-antibody (Ag-Ab) complexes
Where do the Ag-Ab complexes deposit in Type III hypersensitivity?
In tissues
What cells are activated in Type III hypersensitivity?
Macrophages and neutrophils
What is the result of macrophage and neutrophil activation in Type III hypersensitivity?
Tissue destruction
What is another name for Type IV hypersensitivity?
Delayed hypersensitivity
Who first described Type IV hypersensitivity in 1890?
Robert Koch
What pathogen was involved in Robert Koch’s discovery of Type IV hypersensitivity?
Mycobacterium tuberculosis (Mtb)
What type of cells play a major role in Type IV hypersensitivity?
Sensitized T cells, usually Th1 cells
Are antibody and complement directly involved in Type IV hypersensitivity?
No
How long is the initial sensitization phase in Type IV hypersensitivity?
1 to 2 weeks
How long does it typically take for symptoms to develop upon subsequent exposure to the antigen in Type IV hypersensitivity?
Several hours to reach a peak 48 to 72 hours after exposure
What is a classic example of a delayed hypersensitivity reaction?
The skin test for exposure to tuberculosis (TB)
What principle is the TB skin test based on?
Soluble antigens from M. tuberculosis induce a reaction in individuals exposed to the tuberculosis microorganism or a related organism
What is observed at 48 and 72 hours after injecting a small amount of antigen under the skin in the TB skin test?
Presence of induration (lesion ≥10 mm in diameter)
How is the diagnosis of latex allergy determined?
By patient history and immunologic testing
What tests are available to measure latex-specific IgE?
FDA-approved in vitro tests
