Antibodies to private and public HLA class I epitopes in platelet recipients.
BACKGROUND
Transfusions or pregnancies can cause immunization against private HLA determinants and public epitopes shared by more than one private HLA antigen. HLA antibodies are correlated with febrile transfusion reactions, lower platelet response following platelet transfusion, and an increased rate of renal transplant rejection. Until now, antibody specificities in alloantisera from platelet recipients have been poorly characterized.


METHODS
Consecutive serum screens from platelet recipients were analyzed for antibodies against private HLA class I antigens and public HLA epitopes using a serum analysis program based on the 2 x 2 table analysis of correlations. Serum screens of highly immunized patients and of patients with new alloimmunization events were reviewed separately.


RESULTS
Of the serum screens from 566 platelet recipients, 1577 indicated alloimmunization (panel-reactive antibodies >5%). The program assigned a specificity in 1024 of these screens (64.9%) and at least once in 522 of 566 patients (92.2%). In 267 patients, antibodies detecting public epitopes in the combined A- or B-locus cross-reacting groups were found; other public markers were detected in 39 patients. Patterns of reactivity were remarkably less stable than in patient groups previously studied. In many patients, antibodies with apparent private epitope specificity preceded the identification of antibodies against a shared marker of the same cross-reactive group. However, the disappearance of antibodies (whether or not this was followed by a new antibody against a private or public marker belonging to another cross-reacting group) was also observed.


CONCLUSIONS
The computerized analysis of microlymphocytotoxicity tests enhances the rate of antibody specification in sera from platelet recipients with lymphocytotoxic antibodies. The identified antibodies should be taken into account in the selection of platelet donors. The data confirm and extend previous observations on HLA class I antibodies and elucidate new alloimmunization events.
Zimmermann
R
R
Department of Transfusion Medicine and Hemostaseology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany. robert.zimmermann@trans.med.uni-erlangen.de
Wittmann
G
G
Zingsem
J
J
Blasczyk
R
R
Weisbach
V
V
Eckstein
R
R
D000906:Antibodies / Q000097:blood; D000918:Antibody Specificity; D016824:Antigens, Human Platelet / Q000276:immunology; D001782:Blood Donors; D001792:Blood Platelets / Q000276:immunology*; D003601:Cytotoxicity Tests, Immunologic; D000939:Epitopes / Q000276:immunology; D006648:Histocompatibility; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007114:Immunization; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012984:Software
D000906:Antibodies; D016824:Antigens, Human Platelet; D000939:Epitopes; D015395:Histocompatibility Antigens Class I