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- Title
HPA-1a antibody potency and bioactivity do not predict severity of fetomaternal alloimmune thrombocytopenia.
- Authors
Ghevaert, Cedric; Campbell, Kate; Stafford, Prachi; Metcalfe, Paul; Casbard, Angela; Smith, Graham A.; Allen, Dave; Ranasinghe, Edmund; Williamson, Lorna M.; Ouwehand, Willem H.
- 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 × 109 per L (n = 52), and those with a PLT count of at least 20 × 109 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 × 109 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.
- Subjects
THROMBOCYTOPENIA; BLOOD platelet disorders; IMMUNOGLOBULINS; SERUM; BLOOD plasma; MONOCLONAL antibodies; ARTERIAL injuries
- Publication
Transfusion, 2007, Vol 47, Issue 7, p1296
- ISSN
0041-1132
- Publication type
Article
- DOI
10.1111/j.1537-2995.2007.01273.x