18th Page Flashcards
What is the Type I hypersensitivity skin test?
Skin test / Prick test
A. Cutaneous B. Intradermal - more sensitive
What indicates a positive reaction in a Type I hypersensitivity skin test?
Formation of a wheal that is 3 mm greater in diameter than the negative control.
What is the Radio Immunosorbent Test (RIST)?
A competitive RIA test for Total IgE.
What is the Radioallergosorbent Test (RAST)?
A non-competitive RIA test for Specific IgE.
Skin and Prick test
Cutaneous and Intradermal (more sensitive)
What is the Direct Antiglobulin Test (Coomb’s test) used for?
Test for Hemolytic Disease of the Newborn (HDN)
Hemolytic Transfusion Reactions (HTR), and
Autoimmune Hemolytic Anemia (AIHA).
What is the purpose of Direct Fluorescence examination?
To examine renal tissue biopsy for Goodpasture’s syndrome.
What does Indirect fluorescence immunoassay detect In Type II?
Autoantibodies.
What tests are used for autoantibodies in autoimmune disorders in Type III?
LIF
Latex agglutination
Immunoassays
Fluorescent staining.
What is the gold standard test for contact dermatitis (Type IV)?
Patch test.
This test must be done when the patient is free of symptoms or at least has a clear test site.
What indicates a positive patch test?
Redness with papule or tiny blister.
What is the Mantoux Method/Tuberculin Test/PPD?
A test using 0.1 mL of 5 tuberculin units (TU) of PPD injected intradermally into the forearm.
When is an induration considered positive in the Mantoux test?
An induration of 15 mm or more in individuals with no risk factors.
What is a positive Mantoux test result in high-risk groups?
Recent immigrants of high prevalence countries
intravenous drug users
employees of heath care
persons with clinical condition
children younger than 5 yrs old
A reaction of 10 mm or greater
What indicates a positive result for individuals with HIV or immunosuppression?
or chest x-ray with tuberculosis
recent contact with TB
An induration reaction of 5 mm or more.
What does a positive Mantoux test indicate?
Previous exposure to M. tuberculosis or a related organism, but not necessarily an active infection.
positive test results in Mantoux method can also occur in:
Persons who have previous BCG (Bacillus Calmette Guerin) vaccine for tuberculosis.
It uses M. tuberculosis Ag extract prepared from PPD (purified protein derivative )
Mantoux/tuberculin/PPD test
What is Humoral Immunity?
B-cell deficiency.
What is Cellular Immunity?
T-cell deficiency.
What is a defect of phagocytic function?
It is characterized by the inability of a phagocyte to kill ingested microorganisms due to enzyme deficiency in NADPH oxidase or impaired oxidative/respiratory burst.
Humoral Immunity examples
TSCX
Transient hypogammaglobulinemia of infancy
Selective IgA deficiency
Common variable immunodeficiency
X-linked agammaglobulinemia/Bruton’s agammaglobulinemia
What is Selective IgA deficiency?
It is the most common immunodeficiency.
What is X-linked agammaglobulinemia?
Patients lack circulating mature CD19 positive B cells and exhibit a deficiency of immunoglobulins of all classes.
The underlying genetic mechanism is a deficiency of an enzyme called Bruton’s tyrosine kinase in B-cell progenitor cells.
What is DiGeorge syndrome?
It is a developmental abnormality of the third and fourth pharyngeal pouches that affects thymic development.
What is Purine Nucleoside Phosphorylase (PNP) Deficiency?
affects an enzyme involved in the metabolism of purines, leading to decreased T cell numbers due to toxic metabolite accumulation called Deoxyguanosine triphosphate
Examples
Severe combined immunodeficiency (SCID)
Wiskott-Aldrich Syndrome
What is Ataxia-telangiectasia
Combined deficiency of T and B cells
What is Wiskott-Aldrich Syndrome?
It is characterized by a triad of eczema, thrombocytopenia, and immunodeficiency.
What is Chronic Granulomatous Disease (CGD)?
Both sex-linked/autosomal recessive are normal but function abnormally
It is characterized by a phagocyte’s inability to kill ingested microorganisms due to enzyme deficiency (NADPH oxidase)
Macrophage-rich granulomas ae in liver, spleen, etc
Macrophage-rich granulomas can be found in the liver, spleen, and other organs.
What is the Nitroblue Tetrazolium Reduction Test?
It tests the ability of white blood cells to reduce yellow water-soluble tetrazolium to a BLUE insoluble formazan.
Normal WBC: able to reduce; CGD: remains yellow, colorless.
What is the Flow Cytometry Test?
It uses Dihydrorhodamine to assess the fluorescence of white blood cells when it is reduced
Normal WBC: fluorescence when reduced; CGD: no fluorescence.
Bruton Tyrosine Kinase (BTK)
enzyme deficiency in B cell progenitor cells Bruton’s agammaglobulinemia (X-linked)
CGD IN Nitroblue Tetrazolium Reduction
Chronic Granulomatous Disease ??
Yellow/Colorless
CGD in flow Cytometry
Chronic Granulomatous Disease ??
No fluorescence
