Immunodiagnosis

Question 1

how can serological applications be preformed? (mechanisms)

Answer 1

using antibodies to detect antigens (see if someone has infection) or antigens to detect antibodies (to see if someone HAS had that infection)

Question 2

what is the difference between agglutination and precipitation

Answer 2

A- particles
P- soluble proteins

Question 3

what is an agglutination based assay on cards?

Answer 3

used to identify antigens that are particles (like a bacteria or Red cells)

Question 4

how does agglutination based assays work?

Answer 4

cross linking aggregation (usually uses latex particles coated in antigen to detect)

Question 5

what is passive agglutination?

Answer 5

soluble molecule (bacterial antigen or antibody) attached to carrier like latex

Question 6

what is the difference between indirect/passive agglutination ad reverse passive agglutination?

Answer 6

indirect: antigen on latex used to DETECT ANTIBODIES
reverse: antibody on latex used to detect antigen in patients serum

Question 7

what is a titer on agglutination based assay?

Answer 7

last dilution to still show agglutination

Question 8

what is prozone?

Answer 8

antigen is completely covered with antibody molecules so no cross linking can occur

Question 9

what is used to dest for RF?

Answer 9

human IgG coated latex particles and RF (IgM in rheumatoid arthritis patients that reacts with human IgG)

Question 10

what does secondary antibody do for agglutination reactions?

Answer 10

helps to avoid false negatives in the prozone (binds to primary antibody which is already attached to antigen, bridging antigen bound primary antibodies together causing visible aggregates making test more sensitive)

Question 11

what are the limitations of the agglutination test?

Answer 11

positive result does not necessarily mean pt is sick, person may have recovered

Question 12

what could cause a false negative test result?

Answer 12

poor producer of antibody

Question 13

what can cause a false positive test result?

Answer 13

if an unrelated antibody reacts with the antigen nonspecifically

Question 14

what is a quantitative precipitation curve?

Answer 14

using a constant amount of antibody you titrate variable amounts of antigen to get to the equivalence zone (marked by precipitation)

Question 15

In a quantitative precipitation curve, what is the antibody excess zone?

Answer 15

not enough antigen molecules for cross link to form stable complex, no precipitation

Question 16

In a quantitative precipitation curve what is the equivalent zone?

Answer 16

antigen-antibody ratio is in good proportion for cross linking to form large aggregates- precipitation

Question 17

In a quantitative precipitation curve what is the equivalence point?

Answer 17

no antigen or antibody in solution, they are completely precipitated out

Question 18

In a quantitative precipitation curve what is the antigen excess zone?

Answer 18

each molecule of antibody is saturated with antigen, insufficient cross linking, o precipitation

Question 19

what is a precipitation based assay?

Answer 19

add antigen to one well and antibody to another well, solutions diffuse out and bind where they meet precipitation
line forms at the equivalence point

Question 20

in an immunodiffusion test what is a line of identity?

Answer 20

antibody prep recognizes identical antigenic epitopes (lines equal on both sides)

Question 21

what are lines of non-identify in immunodiffusion?

Answer 21

lines extend to both sides of the wells and diffuse past each other, antibody prep recognizes different antigens or antigen epitopes(lines cross each other making a # shape)

Question 22

what are lines of partial identity or spurs?

Answer 22

one antigen has two epitopes and other only has one causing one side to cross but not other leaving a spur)

Question 23

What does radial immunodiffusion test for?

Answer 23

normal levels if IgG

Question 24

what are monoclonal antibodies?

Answer 24

(superior reagents)
all the antibody molecules have the same specificity and recognize the same epitope

Question 25

what is hybridoma tecnology?

Answer 25

allows you to take cells from the spleen and make a lot of a specific antibody

Question 26

what is immunohistochemistry?

Answer 26

antibody conjugated with fluorescent tag that can be seen as it tags appropriate antigen

Question 27

what is FACS?

Answer 27

laser equipment detects fluorescence on individual cells one by one and can sort them

Question 28

what is ELISA?

Answer 28

enzyme is conjugated to secondary antibody by tagging antibody with enzyme, add substrate, and see if a color develops which means positive test

Question 29

what is western blot?

Answer 29

taking antigen and dissociating the proteins on agar gel then blot on membrane with sample and sort