title: Immunoglobulin G subclasses of anti-human platelet antigen 1a in maternal sera: relation to the severity of neonatal alloimmune thrombocytopenia.
abstract: The monoclonal antibody immobilization of platelet antigen (MAIPA) technique was employed to detect and semiquantitatively assess total IgG anti-HPA-1a and its subclasses in sera of mothers who gave birth to severely thrombocytopenic (< 50 x 10(9) platelets/L)(n = 14) or mildly thrombocytopenic/unaffected (> 50 x 10(9) platelets/L)(n = 13) neonates. There was no statistically significant difference between the IgG anti-HPA-1a subclass composition of the 2 groups of sera. The majority of sera (26/27, 96%) showed IgG1 + IgG3 while 17/27 (63%) had all 4 subclasses of the antibody. No significant differences between the severely thrombocytopenic and mildly thrombocytopenic/unaffected groups were detected in the levels of IgG, IgG1, IgG2 or IgG4 of the antibody. However, the values of IgG3 anti-HPA-1a were significantly higher in the severely thrombocytopenic than in the mildly thrombocytopenic/unaffected group of sera with only little overlap (median 2.94 vs. 1.68, range 1.36-9.71 vs. 1.50-2.84, respectively; p < 0.01). The results suggest that maternal IgG3 anti-HPA-1a has predictive value for severe thrombocytopenia of the neonate. However, a prospective study of IgG HPA-1a subclasses in a greater number of maternal sera at different times of pregnancy is needed to test if IgG3 anti-HPA-1a is predictive of the degree of fetal/neonatal thrombocytopenia.
authors.affiliation: Department of Haematology, Imperial College School of Medicine at St Mary's, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Mawas
authors.forename: E
authors.initials: E
authors.lastname: Wiener
authors.forename: L M
authors.initials: LM
authors.lastname: Williamson
authors.forename: C H
authors.initials: CH
authors.lastname: Rodeck
mesh_terms: D016824:Antigens, Human Platelet / Q000276:immunology*; D005260:Female; D005315:Fetal Diseases / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification*; D007231:Infant, Newborn; D039661:Integrin beta3; D007519:Isoantigens / Q000276:immunology*; D011247:Pregnancy; D013921:Thrombocytopenia / Q000276:immunology*
chemical_list: D016824:Antigens, Human Platelet; C061248:ITGB3 protein, human; D007074:Immunoglobulin G; D039661:Integrin beta3; D007519:Isoantigens