HPA-1a antibody potency and bioactivity do not predict severity of fetomaternal alloimmune thrombocytopenia

GHEVAERT, Cedric, CAMPBELL, Kate, STAFFORD, Prachi, METCALFE, Paul, CASBARD, Angela, SMITH, Graham A, ALLEN, Dave, RANASINGHE, Edmund, WILLIAMSON, Lorna M and OUWEHAND, Willem H (2007). HPA-1a antibody potency and bioactivity do not predict severity of fetomaternal alloimmune thrombocytopenia. Transfusion, 47 (7), 1296-1305.

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Abstract

BACKGROUND - The antenatal management of fetomaternal alloimmune thrombocytopenia (FMAIT) due to HPA-1a antibodies remains controversial, and a test identifying pregnancies that do not require therapy would be of clinical value.

STUDY DESIGN AND METHODS - The statistical correlation was analyzed between clinical outcome and 1) anti-HPA-1a potency in maternal serum samples determined by a monoclonal antibody immobilization of platelet (PLT) antigen assay with an international anti-HPA-1a potency standard and 2) anti-HPA-1a biological activity measured by a monocyte chemiluminescence (CL) assay.

RESULTS - A total of 133 pregnancies with FMAIT due to anti-HPA-1a were analyzed. In 97 newly diagnosed cases, there was no difference in antibody potency or CL signal between cases with intracranial hemorrhage (ICH; n = 15), those with no ICH but a PLT count of less than 20 x 10(9) per L (n = 52), and those with a PLT count of at least 20 x 10(9) per L (n = 30). In 22 previously known pregnancies, the positive predictive value of maternal anti-HPA-1a of greater than 30 IU per mL for a PLT count of less than 20 x 10(9) per L was 90 percent, but the negative predictive value was only 66 percent. Antibody potency tended to stay stable throughout pregnancy (n = 16) and from one pregnancy to the next (n = 16).

CONCLUSION - Neither severe thrombocytopenia nor ICH in HPA-1a-alloimmunized pregnancies can be predicted with sufficient sensitivity and specificity for clinical application from maternal anti-HPA-1a potency or bioactivity.

Item Type:	Article
Additional Information:	Article first published online: 2 MAY 2007
Research Institute, Centre or Group - Does NOT include content added after October 2018:	Biomedical Research Centre
Page Range:	1296-1305
Depositing User:	Jamie Young
Date Deposited:	03 Jun 2015 13:33
Last Modified:	18 Mar 2021 18:45
URI:	https://shura.shu.ac.uk/id/eprint/9998

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