Antibody Identification Case Studies

109 Pages·2017·0.94 MB·English

Antibody Identification
Case Studies
Karen Rodberg, MBA, MT (ASCP) SBB
Director, Immunohematology Laboratory
American Red Cross, Southern California Region
The need is constant.
The gratification is instant.
Give blood.TM
Commonly used problem-solving techniques:
– Proteolytic enzymes
– Reducing (thiol) reagents
– Titration and neutralization
– Adsorption
– Elution
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Enzyme use for antibody i.d.
• Antibody identification tool
- Weak or equivocal reactions
- Suspected multiple antibodies
- Characterize unknown specificity
• Adsorption studies
- Remove or separate antibodies
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Proteolytic Enzymes
Proteases: cleave bonds in appropriate
amino acid chains of membrane
bound proteins or glycoproteins
Ficin (figs)
Papain (papayas)
Bromelin (pineapples)
Trypsin (bovine/porcine pancreas)
-Chymotrypsin (pancreas)
Pronase (Streptomyces griseus)
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Effects of enzyme-treatment of RBCs
• Proteases remove sialic acid-bearing
glycoproteins → reduction in:
- Cell surface negative charge
- Steric hindrance
- Membrane-bound water
• Results in:
 RBCs closer together so IgG can
span distance → agglutinate
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Other effects on RBCs
Effect on RBC antigens:
• Some antigens are denatured
• Some antigen-antibody
reactivity is enhanced
Therefore not used for routine
antibody detection, but very
useful in antibody identification
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Example – MNS System
- Cleave [  ] large
portions of
glycoproteins (e.g.,
GPA, GPB) from RBC
- Site of action is
enzyme-specific
- Carbohydrates
attached to the portion
of protein affected will
also be removed
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Enzymes can denature or enhance:
Antigen denaturation (ficin/papain)
M, N, S, EnaTS, EnaFS,
Fya, Fyb, Fy6, Ge2, Ge4, Inb,
Ch, Rg, JMH, Pr, Xga, s*, Yta*
*variable
Antigen-antibody reactivity enhancement
P , I, i, Lewis, Rh, Kidd, Colton,
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Dombrock
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Case Study #1 – case history
33 y.o. female obstetrical patient
Full term delivery
No prenatal care
4th pregnancy
Case Study #1
ABO group Rh type
A B
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Anti-A Anti-B RBCs RBCs Anti-D Cntl
0 0 4+ 4+ 0 0
Interpretation: Group O Interpretation: Rh negative
PEG
D C E c e Lea Leb P M N S s K k Fya Fyb Jka Jkb RT IAT
1
+ + 0 0 + + 0 + + + 0 + 0 + 0 + + 0 1+ 3+
I
+ 0 + + 0 0 + + 0 + + + + + + 0 + + 0 3+
II
0 0 0 + + 0 + + + 0 + 0 0 + + + 0 + 2+ 1+
III
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