Evaluation of an enzyme-linked immunosorbent assay kit (GTI PakPlus) for the detection of antibodies against human platelet antigens.
Twenty-six serum samples from 24 patients were investigated for the presence of platelet-specific antibodies in a partly retrospective (n = 15) and partly prospective (n = 9) study. The sera contained either alloantibodies to human platelet antigens (HPA) (n = 23) or were from clinically suspected cases of fetomaternal alloimmune thrombocytopenia (FMAITP) in which platelet-specific antibodies had not been detected (n = 3). Three techniques were used to detect platelet antibodies: the platelet immunofluorescence test, the monoclonal antibody immobilization of platelet antigens (MAIPA) assay and a commercially available enzyme-linked immunosorbent assay--GTI PakPlus (GTI kit). Two alkaline phosphatase-conjugated antiglobulin reagents provided by the manufacturer were used in the GTI kit: an antihuman IgG/IgA/IgM (IgGAM) conjugate and an antihuman IgG conjugate. The GTI kit with the anti-IgGAM conjugate failed to detect eight antibody specificities in seven sera (anti-HPA-1a [n = 3], anti-HPA-3a [n = 1], anti-HPA-3b [n = 1] and anti-HPA-5b [n = 3]). Greater signal-to-background ratios were achieved in the GTI kit with the anti-IgG conjugate but five antibody specificities (anti-HPA-1a [n = 1], anti-HPA-3a [n = 1], anti-HPA-3b [n = 1], anti-HPA-5b [n = 2]) remained undetectable. All the sera were detected by MAIPA assay and, furthermore, the MAIPA assay achieved the greatest signal-to-background ratio in the majority of sera tested. These findings re-emphasize the value of the MAIPA assay in reference laboratories and illustrate that the GTI kit may either fail to detect or incorrectly identify clinically significant HPA antibodies.
Lucas
G F
GF
International Blood Group Reference Laboratory, Bristol, UK. geoff.lucas@nbs.nhs.uk
Rogers
S E
SE
D016824:Antigens, Human Platelet / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology*; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use*; D008431:Maternal-Fetal Exchange; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000276:immunology*
D016824:Antigens, Human Platelet; D016756:Immunoglobulins, Intravenous