Antibody Identification Flashcards
agency that controls blood bank reagents
Bureau of Biologics of FDA
types of blood bank reagents
high protein, monoclonal, chemically modified, human-derived
ABO reagents
commercially prepared anti-A, anti-B, anti-A,B, anti-A1, A1 and B cells
RH reagents
- monoclonal IgM antibody reactive at room temp
- monoclonal polyclonal blend includes IgG antibody for weak D detection
uses of indirect antiglobulin test
antibody screen/panel crossmatch weak D testing leukocyte and platelet antibody test detection of autoantibodies
uses of direct antiglobulin test
detection of autoantibodies
HDFN
transfusion reactions
RBC sensitization by drugs
examples of enhancement media
LISS PEG 22% bovine serum albumin gel column agglutination solid-phase technology
what should be suspected if autocontrol is positive but DAT is negative?
antibodies to LISS and PEG enhancement media ingredients
mechanism: LISS
low ionic strength saline; reduced ionic strength in comparison to normal saline
which enhancement media(s) is used to enhance reactivity and decrease incubation time for antibody identification?
LISS, PeG
which enhancement media may enhance autoantibodies?
LISS
mechanism: PeG
polyethylene glycol; linear polymer that is water-soluble; steric exclusion of water molecules in the diluent
what enhancement may enhance warm autoantibodies?
PEG
what enhancement enhances detection of clinically significant antibodies along with decreasing detection of clinically insignificant antibodies?
PEG
mechanism: 22% bovine serum albumin
helps reduce repulsive charges between red cells during antibody detection, promoting agglutination
what enhancement may enhance cold autoantibodies?
22% bovine serum albumin
principle use of enhancement media
reduce incubation time and increase reaction strength
what media enhances linked lattice formation by reducing net negative charge of red cells, allowing the cells to come closer together?
albumin
what media enhances antibody uptake by reducing zeta potential and allowing increased attraction between positively charged antibodies and negatively charged red cells?
LISS
what media enhances antibody-antigen binding by excluding water from around the red cells, effectively concentrating the antibody and favoring binding to its target antigen?
PEG
what media enhances linked lattice formation by decreasing the net negative charge of the red cells by removing sialic acid residues to allow the red cells to come closer together?
enzyme treatment
what media enhances formation of the linked lattice by neutralizing the negative charges of the sialic acid residues on the red cells, allowing red cells to get closer together?
polybrene
media that can enhance reactivity of weak Kidd and Duffy antibodies
PEG
enhancement that may not pick up IgM antibodies such as ABO or Lewis
PEG
enhancement that can result in spontaneous agglutination
polybrene
avidity
speed at which standardized endpoint is attained (strength)
titer
reciprocal of greatest dilution that gives 1+ agglutination (amount)
requirements at reagent arrival
dated and stored at optimal temp
expiration date and appearance noted and recorded
QC of antigen typing sera
heterozygous positive control
negative control
naturally occurring antibody common class
IgM
immune stimulated antibody common class
IgG
antibodies to substances in the environment that are antigenically similar to red cell antigens are ___ (naturally occuring or immune stimulated)
naturally occurring
definition: clinically significant antibody
causes HDFN or HTR or noticeable decrease in transfused red cell survival
preanalytical patient medical history considerations in antibody identification
transfusion, pregnancy, disease, drugs, rare phenotype
analytical considerations in antibody identification
specimen requirements, reagents, serological procedures, factors affecting antibody identification
p value requirement of antibody identification
<0.05
causes of positive autocontrol
autoantibodies (Warm and cold)
recent transfusion/DHTR
drug-induced issues
passively acquired antibodies
source of ficin
figs
source of papain
papaya
source of trypsin
pig stomach
source of bromelin
pineapple
antigens destroyed by enzyme treatment
M, N, Fya, Fyb, Xga, JMH, Ch, Rg
antigens enhanced by enzyme treatment
Rh, Lewis, Kidd, P, I
mechanism of enzyme treatment
cleave membrane glycoproteins and sialic acid residues that link amino acid chains together
antigens unaffected by enzyme treatment
Kell
Diego
Colton
mechanism of thiol reagents
disrupt disulfide bonds that connect J chain of IgM molecule; denatures IgM molecules so they can’t agglutinate or bind complement
thiol reagents
DTT
2-ME
AET
reagent used to distinguish IgM from IgG
thiol
what enzyme denatures CD38 antigen
thiol
antibody seen in Dara patients
anti-CD38
thiol reagent effect on Kell antigens
destroys
mechanism of ZZAP
denatures DTT sensitive antigens along with antigens that are sensitive to enzymes
mechanism of chloroquine diphosphate
dissociate IgG from red cell membrane; weakens class I HLA antigen expression along with other antigens including Rh
reagent used to remove bound antibody so cells can be antigen typed using antisera that require IAT testing
glycine acid/EDTA, chloroquine diphosphate
what antibodies can be enhanced by lowering pH to 6.5
anti-M, some anti-U
how to lower pH to 6.5
1 volume 0.1N HCl to 9 volumes serum
lowering pH to <6.0 can decrease or diminish reactivity of what blood groups
Rh, Duffy, Kidd
Lewis inhibition substance
saliva of individual with Lewis gene
P1 inhibition substance
hydatid cyst fluid, pigeon eggs
Sda inhibition substance
urine from Sda positive individual
Chido and Rodgers inhibition substance
plasma from Ch+Rh+ individual
what is required to interpret results from inhibition techniques?
overall test result is nonreactive and dilution control is negative
mechanism: adsorption
antibodies removed from patient serum by adsorbing onto red cells which express the corresponding antigen
normal serum:cell ratio for adsorption
1:1
mechanism: elution
bound antibody is released by changing of thermodynamics to recover bound antibody into usable form
heat/freeze-thaw elution use
ABO incompatibility from ABO HDFN
acid/organic solvent elution use
warm autoantibodies and alloantibodies
mechanism: titration
testing twofold serial dilutions of patient’s serum with preselected red blood cells to provide relatively how much antibody is present in patient’s serum or given strength of red blood cell antigen expression
