Use of enzyme treatment to enhance reactivity of HLA and platelet-specific antibodies in solid-phase RBC adherence assays.
BACKGROUND
Solid-phase RBC adherence (SPRCA) assays (Immucor) detect HLA and/or platelet-specific antibodies. Pretreatment of reagent platelets with enzymes was investigated to determine whether the sensitivity of the assay could be increased.


METHODS
SPRCA testing, following the manufacturer's directions, was performed on 51 sera from patients with either a positive SPRCA antibody screen, suboptimal clinical responses to platelet transfusions, and/or suspected immune thrombocytopenic purpura; testing was also performed following pretreatment of the reagent platelets with bromelin, papain, or ficin. Sera from 23 patients having negative routine SPRCA antibody screens and good clinical responses to transfusion were tested as controls. Lymphocytotoxic antibody testing was also performed on selected samples. The effectiveness of enzyme treatment was judged by the increase in the proportion of reagent platelets reacting with the sample and the observed reaction strengths.


RESULTS
Pretreatments of reagent platelets with all three enzymes increased the reactivity of known antibodies and detected some HLA and platelet-specific antibodies that had not reacted in routine testing. The clinical significance of the antibody specificities detected only after enzyme pretreatment was verified by a correlation with results from transfusing antigen-negative units. Only occasional false-positive results after enzyme pretreatment were observed.


CONCLUSIONS
The use of enzyme pretreatment of SPRCA screening strips can provide information that is useful in selecting appropriate units for transfusion.
Leach
Miriam Fogg
MF
Transfusion Service Laboratory, Department of Pathology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA. miriam.k.leach@hitchcock.org
AuBuchon
James P
JP
D000918:Antibody Specificity; D001323:Autoantibodies / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000276:immunology*; D001963:Bromelains / Q000494:pharmacology; D002448:Cell Adhesion; D004797:Enzyme-Linked Immunosorbent Assay; D004798:Enzymes / Q000494:pharmacology*; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D005361:Ficain / Q000494:pharmacology; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007202:Indicators and Reagents; D007518:Isoantibodies / Q000097:blood*; D015470:Leukemia, Myeloid, Acute / Q000276:immunology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010206:Papain / Q000494:pharmacology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology; D017713:Platelet Transfusion; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D004798:Enzymes; D006680:HLA Antigens; D007202:Indicators and Reagents; D007518:Isoantibodies; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D001963:Bromelains; D010206:Papain; D005361:Ficain