indirect antiglobulin testing

Question 1

immediate spin test

Answer 1

• IgM antibodies
• direct test

Question 2

37C incubation

Answer 2

• detects complement
• IgG antibody

Question 3

coombs test

Answer 3

• IgG lattice with IgM addition
• removal of unbound material in plasma
• enhancements

Question 4

LISS

Answer 4

reduce zeta potential

Question 5

PEG

Answer 5

remove water volume

Question 6

albumin

Answer 6

increase collisions

Question 7

bromelin

Answer 7

reduces steric hinderence

Question 8

polybrene

Answer 8

polymer non specific binding

Question 9

purpose for monoclonal reagents

Answer 9

binding site specificity for what we want only - reduce false pos

Question 10

purpose for cell washer

Answer 10

wash step for vol and number of washes standardized - reduce false neg

Question 11

solid phase

Answer 11

splits open red cells to better adhere and read

Question 12

when are enhancements used

Answer 12

before incubation period to reduce time

Question 13

indirect testing

Answer 13

• what has attached to cell in vitro
• is there antibody present
• what we run in lab with 37 incubation
• in vitro

Question 14

direct testing

Answer 14

• hase Ab found Ag within the body
• in vivo

Question 15

antibody screen

Answer 15

presence of clinically significant immune stimulated (IgG) antibodies in patient plasma

Question 16

IAT

Answer 16

indirect antibody test -> coombs

Question 17

which of the following reagents is used to facilitate hemafflutination following the sensitization of red cells with IgG antibody
- anti human globulin
- low ionic strength saline
- polyethylene glycol
22% bovine albumine

Answer 17

anti human globulin
- coombs reagent to help IgG cells to agglutinate

Question 18

after the addition of IgG coated RBCs (check cells) to a negative AHG reaction during Ab screen, a negative reaction is observed. Which of the following is the correct interpretation?
- Ab screen is neg
- Ab screen needs to be repeated
- saline wash was adequate
- Ab screen is pos

Answer 18

Ab screen needs to be repeated
- check cells should not be negative reactions, anti Ab added preferentially bound circulating Ab not red cell bound Ab

Question 19

coombs test reagent

Answer 19

anti-human antiglobulin
- IgM anti - IgG

Question 20

what is the purpose for anti-antibody addition in coombs test

Answer 20

• grabs red cell bound IgG (multiple) to form agglutination lattices

Question 21

describe check cells

Answer 21

IgG coated cells
- determine adequate washing of coombs phase

Question 22

if a check cell reaction is negative what does that indicate

Answer 22

inadequate washing, AHG bound circulating Ab not red cell IgG, repeat teting

Question 23

which is more likely in coombs phase: false neg or false pos

Answer 23

false neg

Question 24

list possible false negatives in coombs testing AHG step

Answer 24

• incorrect ratio of plasma to red cells
• aged/hemolyzed cells
• excessive washing
• bad centrifuge calibration
• leftover wash dilution

Question 25

list possible false negatives in check cell step of coombs testing

Answer 25

• leftover Ab bound check cells
• insufficient washing
• insufficient incubation

Question 26

lab controlled antigen-antibody binding

Answer 26

• time
• temp
• centrifugation

Question 27

antibody- antigen controlled factors

Answer 27

• affinity
• avidity
• zeta potential
• steric hinderance
• hydrophobic` bond

Question 28

describer gel reactions

Answer 28

precipitation

Question 29

describe solid phase reaction

Answer 29

adherence