Lecture 18 - Immunodiagnostics

Question 1

Define:

Antigen

Answer 1

molecule that can bind BCR/TCR (usually associated with pathogens)

Question 2

Define:

Antibody

Answer 2

antigen-binding (specific) protein produced by B cells

Question 3

What does the “nature” of antigen diagnostic tests work with

Answer 3

how the binding will occur

Question 4

What three binding-based tests are there

Answer 4

1. agglutination (complex)
2. precipitation (soluble)
3. flocculation

Question 5

What does antibody function diagnostic test work with

Answer 5

how the antibody neutralizes the antigen

Question 6

What are the three antibody functions that respective tests look at

Answer 6

1. neutralization
2. complement fixation
3. hemolysis

Question 7

What immunoglobulin causes agglutination more effectively? Why?

Answer 7

IgM; it is a pentamer

Question 8

Give an example of an agglutination test

Answer 8

ABO blood typingW\

Question 9

What is the prozone

Answer 9

too many antibodies result in no agglutination

Question 10

what is the post zone

Answer 10

less antibodies but more free-floating antigens

Question 11

what are the limitations of precipitation tests

Answer 11

there needs to be large amounts of antibodies and antigens

Question 12

T/F: in a complement fixation test, the formation of a complex means the complement protein is in use

Answer 12

True

Question 13

a medial line is a precipitation test is considered to be ____ and having ____ amounts of antigen and antibody

Answer 13

positive; equal

Question 14

Fixing means

Answer 14

complement protein is in use

Question 15

what does C3b bind to

Answer 15

antibodies

Question 16

How do fluorescent antibody techniques work

Answer 16

detect specific molecules/structures on or within cells

Question 17

direct FAT

Answer 17

single fluorescent labeled antibody binding to target antigen

Question 18

Indirect FAT

Answer 18

uses two antibodies (primary that binds target and secondary that binds to complex)

Question 19

FITC appears as ____ while PE appears as ____

Answer 19

green; red

Question 20

Flow cytometry

Answer 20

informs us about cell types in blood/tissue

Question 21

Explain the 3 steps of flow cytometry

Answer 21

1. single cells are hit by particular wavelength
2. emitted light detected by the photomultiplier and converted to a digital pulse
3. expressed as dot plot or histogram

Question 22

What are the 4 types of ELISA

Answer 22

1. direct
2. indirect
3. sandwich
4. competitive

Question 23

What is ELISA (enzyme linked immuno-sorbent assay)

Answer 23

a plate based test that detects and measures antibodies in a sample

Question 24

Explain:

direct ELISA

Answer 24

primary antibody is conjugated

Question 25

Explain:

indirect ELISA

Answer 25

primary antibody is unconjugated, need secondary

Question 26

Explain:

sandwich ELISA

Answer 26

detecting antigen
capture antibody (unconjugated) and detection antibody (conjugated)

Question 27

Explain:

competitive ELISA

Answer 27

used to measure concentration of Ag/Ab in sample by detecting interference

Question 28

What is the interpretation of:

+ antigen, + antibody

Answer 28

acute infection

Question 29

What is the interpretation of:

+ antigen, - antibody

Answer 29

early infection

Question 30

What is the interpretation of:

• antigen, + antibody

Answer 30

previous infection

Question 31

What is the interpretation of:

• antigen, - antibody

Answer 31

negative (no current or past infection)