MLT 269 Serology Study Guide Flashcards
Principle or clinical significance of direct fluorescent antibody test
A known Ab is labeled with a fluorescent dye and added to unknown Ag that is fixed to a slide. After incubation and was the slide is read using a fluorescent scope.
Ab-Ag rxn shows bright green fluorescence
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for the ELISA
Competitive: enzyme labeled Ag competes w/ unlabeled pt Ag for binding sites on Ab molecules attached to a solid phase. The more pt Ag is bound the less enzyme labeled Ag can attach.
Non-competitive: higher sensitivity; measure status of immunity for certain agents and for autoantibody testing. Either Ag or Ab is bound to solid phase. When Ag is used for coating, pt Ab is added given time to react. After wash, enzyme labeled Ab is added. This 2nd Ab reacts w/ any pt Ab bound to solid phase. If no pt Ab is bound, the second Ab will not bind. After another wash, enzyme substrate is added. Color development is directly proportional to the amount of pt Ab.
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for the complement fixation test
Complement is used as a reagent. Complement fixation occurs after the binding of Ag and Ab so complement uptake is an indicator of the presence of either specific Ag or Ab. Detects viral, fungal, or rickettsial Abs. Test uses an Ag and Ab, one of which is unknown, and sheep rbcs coated w/ hemolysin which will lyse in presence of complement. If lysis occurs in Stage 2, complement did not fix during stage 1.
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for the RPR
Flocculation test for syphillis. Based on cardiolipin Ag technique but read macroscopically. Performed on unheated serum or plasma(does not require inactivation) w/ modified VDRL Ag and charcoal particles. Choline chloride replaces heat to inactivate complement.
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for theFTA-ABS
patient serum absorbed with the extract of non-pathogenic Reiter treponeme to remove non-specific treponemal antibodies. a virulent strain of T pallidum(Ag) is allowed to react with the pt serum(Ab). specific T. pallidum Ab attached to the Nichols virulent strain of T. pallidum on a slide are demonstrated with a fluorescein-labeled antiglobulins (makes the Ag-Ab rxn visible) using dark field fluorescence microscopy.
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for the differential absorption test of Davidson
determination of anti-sheep antibodies after absorption with guinea pig kidney and possibly beef RBCs. A positive reaction is indicated by complete removal of anti-sheep agglutinins(Ab) by guinea pig kidney and/or beef RBC/s
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for the RA test
SCREEN: Rheumatoid factor (RF) Ab is found in 80% of pts. Uses agglutination test with latex particles coated with IgG.
DIAGNOSTIC: EIA technique or Nephelometric assays used to test for IgG or IgA isotypes which rarely occur in other diseases. Disease activity is followed by measuring inflammation thru ESR, CRP and complement components.
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for the ANA test.
SCREEN: fluorescent Antinuclear AB; mouse kidney or human epithelial HEp-2 cells are fixed to a slide and allowed to react with pt serum. Fluorescent tagged antihuman immunoglobulin or horseradish peroxidase is added(conjugate)
DIAGNOSTIC: Double stranded DNA Ab are seen only in lupus(50-70%) and levels correlate with disease activity. Produces peripheral or homogenous staining pattern on indirect immunofluorescence.
List the principle and/or clinical significance of, in cluding reagents and pos and neg reactions for cold agglutinins
Keep blood sample at 37 deg C until serum and cells separate. Make serial dilutions of sample serum with human group O as the Ag. Incubate overnight in fridge and view for agglutination. Warm to 37 deg C for 30 mins If agg disappears, then cold agg are present..
High titers that do not vary over time may indidcate mycoplasma pneumonia, IM, autoimmune hemolytic anemia, and viral infections(mumps, rubella, flu, HIV…)
What is the causative agent of syphillis?
IM?
Treponemal pallidum
Epstein-Barr virus
Ig produced first after exposure to an antigen
IgM
Ig found in greatest concentration
IgG
Ig appearing in greatest concentration to a second antigen exposure
IgG
Ig associated with allergic reations
IgE
List the differential absorption characteristics of IM(non-Forssman), Forssman, and serum sickness antibodies.
HAb GPkidney Beef rbc
Forss Yes No
IM No Yes
SeSi Yes Yes
reagin
Ab found in blood of a person with a genetic predisposition for allergies; hay fever; IgE response
Ab formed against lipid material from damaged cells; substance found in the blood of an individual that has a positive reaction to serological syphillis test.
anamnestic reaction
secondary immune response; IgG; 1-2 weeks after primary exposure, faster response, stays higher, longer
Prozone
the failure of a serological reaction to occur, due to antiBody excess
Postzone
the failure of a serological reation to occur, due to antiGen excess
Flocculation
Non-treponemal Ag test. Alcoholic extracts of beef heart tissue(cardiolipin) is mixed with lechithin and cholesterol. THe cholesterol absorps the tissue lipids so agg particles can be seen. RPR and VDRL.
Cross reaction
antibody elicited by one antigen can cross-react with an unrelated antigen; occurs if two different anitgens share an identical or very similar epitope.
Fc
Fc fragment; complement binding region of immunoglobulin molecule
passive acquired immunity
immunity dependent on injection of preformed Ab, or acquired in utero, or mothers milk; transient, last a few weeks.
active acquired immunity
host response to foreign agents that depends on T and B lymphs and is characterized by the presence of Ab that cross-react with heart tissue, specific to antigen and ability to remember prior exposure; natural exposure, vaccination
adoptive immunity
passive immunity resulting from immunization of sensitized lymphs into a host from an immune donor
Fab
region on relatively constant sequence; antigen binding activity
hinge region
flexible portion of the heavy chain that is located between the first and second constant regions. allows molecule to bend to let two Ag-binding site operate independently.
constant region
carboxyl-terminal half of Ig molecule; two basic a.a. sequences; half of Ig light chain or three quarters of heavy chain
variable region
amino-terminal half of Ig molecule, with varying a.a.; responsible for the specificity of a particular Ig molecule
Identify the results seen in syphillis serology with a biologic false positive
a positive due to conditions other than syphillis, such as; drug addiction, vaccinations, malaria, viral/bacterial URI’s
What samples can be used in the RPR and the VDRL?
RPR - plasma or serum
VDRL - serum or CSF; heat inactivated
Give the complement cascade, including subcomponents and what elements are essential in certain complement complexes
C1qrs (requires Ca+2), cleaves C4 and C2(requires Mg) to form C3. Then C5, C6, C7, C8, C9 are formed. C9 polymerizes to cause lysis to the target cell.
List Ig classes that can bind complement
2-IgG, 1-IgM
Differentiate between T and B cells
T; modified in thymus, cellular immunity, 2.2 yrs half-life span; production of sensitized lymphs and their products lymphokines
B; modified in fetal liver/bone marrow, humoral immunity, 3 day lifespan; synthesis and release of AB into blood and body fluids, directly neutralizes Ag
State the titer that indiactes immunity to rubella
10
If an individual is vaccinated for rubella, name the type of immunity this produces
active acquired
Describe the specimen handling for cold agglutinins
keep blood sample at 37 deg C until serum and cells separate
List correct order of appearance of the specific markers (Ab and/or Ag) for hepatitis B infection
HBsAg HBeAg IgM anti-HBc anti-HBe anti_HBs
evaluate the hepatitis disease status of a patient if given the results of hepatitis markers
HBsAg: appears 2-12 wks after exposure to HBV, undetectable by 12-20 wks in acute HBV. Remains elevated in chronic HBV
HBeAg: appears shortly after HBsAg and disappears shortly before HBsAg disappears. Present durin active replication so higher stages of infectivity. PT STAYS INFECTIOUS UNTIL anti-HBe appears.
IgM anti-HBc: indicates current or recent acute infection. appears weeks after HBsAG and stays up to 6 months. Detected btw disappear of HBsAg and appearance of HBs antibodies
anti-HBe: appears shortly after HBeAg disappears, indicates pt is recovering from acute infection.
anti-HBs: appears during recovery of acute infection, weeks to months after HBsAg disappears
mode of transmission for hepatitis viruses
HAV - fecal, oral HBV - blood, sexual, needles, perinatal HCV - blood, sexual, needles, transfusions HDV - blood bourne, only with HBV HEV - fecal, oral
Name the test most widely use to detect HIV antibody
ELISA-screen
western blot-confirmatory
How long on average does it take for a individual to develop HIV antibodies after exposure to HIV virus?
6-12 weeks
What is the RAST used for?
Radioallergosorbent test; in-vitro test to identify specific IgE against allergens; serological determination of antigen-specific IgE. Uses pt serum instead of skin to determine allergies
Multiple myeloma most commonly involves which Ig class?
IgG
What is the main barrier against foreign particle invasion into the body?
unbroken skin
Define window phase as it relates to HIV testing
the length of time after infection that it takes for the virus to become detectable by HIV tests; varies person to person and by test used, but no more than 3 months after exposure.
