blood bank: antigen-antibody reaactions

IgM

first antibody produced in primary immune response

which antibody agglutinates at room temp (cold antibody)

IgM

which is the only antibody that can cross the placenta

IgG

which is a warm antibody

IgG

AHG assists in detecting

RBCs coated in antibodies

the indirect antiglobulin test is used to detect

in vitro activity

IAT process

patient serum is mixed with reagent red cells, AHG is added, cells are incubated, and it is observed for agglutination

direct antiglobulin test is used to detect

in vivo activity

DAT procedure

patient red cells are washed to remove unbound antibody, AHG is added and is observed for agglutination

IAT is mainly used for

antibody screening, panel ID, crossmatching, phenotyping

DAT is mainly used for

post transfusion, drug related antibodies

which AHG reagent is used as a screening reagent

polyspecific AHG

agglutination after the immediate spin phase of an antibody screen indicates

the presence of a cold agglutinin (IgM)

agglutination after the 37C and AHG phase indicates

the presence of a warm agglutinin (IgG)

check cells are used to check for

false AHG negatives

enhancement reagents

increase speed and ability of an antibody to attach to the antigen on RBC

which enhancement reagent inhibits cold reacting agglutinins (IgM)

PEG

which enhancement reagent allows for reducing zeta potential, and enhancing agglutination in Rh antibodies

albumin

which enhancement reagent decreases zeta potential, increases antibody uptake, and shortens incubation time

LISS

what are the two classes of immunoglobulins that are associated with blood bank

IgG and IgM

which antibody is cold reacting to and is very efficient at fixing complement

IgM

which antibody is warm reacting and usually needs AHG to observe agglutination

IgG

which test does the antibody bind to the red cell in the test tube (in vitro)

indirect antiglobulin test (IAT)

which test is the antibody already on the red cell (in vivo)

direct antiglobulin test (DAT)

what are the three phases of antibody screens in tube testing

immediate spin (IS), 37C, AHG

what antibody would you suggest is present if the immediate spin is positive

IgM

what does a negative antibody screen after adding AHG indicate

there are no antibodies present

what so you do if your check cells do not agglutinate

restart the testing process

what are the three enhancement reagents used in screens

albumin, LISS, PEG

why do you perform an auto control with each patient’s antibody screen

to detect auto antibodies

how do you perform an auto control in tube

one drop of washed patient cells to two drops patient serum

what are some reasons for false positive reactions on the screen

collection error, cold reacting autoantibody, contaminated glassware, excessive centrifugation

what are some reasons for false negative reactions on the screen

inadequate washing, waiting too long, bad AHG reagent