Frequencies of maternal platelet alloantibodies and autoantibodies in suspected fetal/neonatal alloimmune thrombocytopenia, with emphasis on human platelet antigen-15 alloimmunization.
OBJECTIVE
Serological evaluation of maternal sera for platelet antibodies in suspected fetal/neonatal alloimmune thrombocytopenia (FNAITP) discloses in only approximately 30% of individuals a platelet-specific antibody. Transfusion-induced alloimmunization against human platelet antigen-15 (HPA-15) has been reported to be about as common as against HPA-5, the second most common platelet antibody. Thus, anti-HPA-15 may also contribute significantly to yet-unclear cases of FNAITP.


METHODS
In this retrospective analysis, we provide data on maternal platelet antibodies from 309 mothers who delivered an offspring with suspected FNAITP.


RESULTS
Genotyping maternal and paternal samples (together n = 573) revealed a gene frequency of 0.496 for HPA-15a and a gene frequency of 0.504 for HPA-15b. HPA-15 antibodies were detected in 2% of all samples. Anti-HPA-15a and -15b were detected in two and three samples, respectively. One serum reacted equally with HPA-15a and -15b platelets. The most frequent platelet-specific antibodies were anti-HPA-1a (22%), but anti-HPA-5b (8.4%) were more frequent than anti-HPA-15. In addition, panreactive (5.5%) or autoreactive (5.2%) anti-GPIIb/IIIa or anti-GPIb/IX were detectable in maternal samples.


CONCLUSIONS
These data indicate that HPA-15 alloimmunization needs only to be considered in subjects with suspected FNAITP if no other platelet-specific antibody is detectable. The presence of panreactive or autoreactive antibodies should also be considered in neonatal thrombocytopenia.
Mandelbaum
M
M
Clinic for Blood Group Serology, Medical University Vienna, Vienna, Austria.
Koren
D
D
Eichelberger
B
B
Auerbach
L
L
Panzer
S
S
D015703:Antigens, CD / Q000235:genetics / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood; D001792:Blood Platelets / Q000276:immunology*; D005260:Female; D005315:Fetal Diseases / Q000276:immunology*; D058851:GPI-Linked Proteins; D005787:Gene Frequency; D006801:Humans; D007114:Immunization; D015994:Incidence; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood; D008297:Male; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology; D011247:Pregnancy; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000276:immunology*
D015703:Antigens, CD; D001323:Autoantibodies; C120523:CD109 protein, human; D058851:GPI-Linked Proteins; D007518:Isoantibodies; D009363:Neoplasm Proteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex