[Superiority of SELDI versus ELISA for certain isoforms]
>>Clin Diagn Lab Immunol. 2005 Jul;12(7):837-44.
Proteomic but not enzyme-linked immunosorbent assay technology detects amniotic fluid monomeric calgranulins from their complexed calprotectin form.
Buhimschi IA, Buhimschi CS, Weiner CP, Kimura T, Hamar BD, Sfakianaki AK, Norwitz ER, Funai EF, Ratner E.
Department of Obstetrics, Gynecology, and Reproductive Science, Yale University School of Medicine, 333 Cedar Street LCI 804, P.O. Box 208063, New Haven, CT 06520-8063. irina.buhimschi@yale.edu.
Four proteomic biomarkers (human neutrophil peptide 1 [HNP1], HNP2 [defensins], calgranulin C [Cal-C], and Cal-A) characterize the fingerprint of intra-amniotic inflammation (IAI). We compared proteomic technology using surfaced-enhanced laser desorption-ionization-time of flight (SELDI-TOF) mass spectrometry to enzyme-linked immunosorbent assay (ELISA) for detection of these biomarkers. Amniocentesis was performed on 48 women enrolled in two groups: those with intact membranes (n = 27; gestational age [GA], 26.0 +/- 0.8 weeks) and those with preterm premature rupture of the membranes (PPROM; n = 21; GA, 28.4 +/- 0.9 weeks). Paired abdominal amniotic fluids (aAFs)-vaginal AFs (vAFs) were analyzed in PPROM women. Quantitative aspects of HNP1-3, Cal-C, Cal-A, and calprotectin (a complex of Cal-A with Cal-B) were assessed by ELISA. SELDI-TOF mass spectrometry tracings from 16/48 (33.3%) aAFs and 13/17 (88.2%) vAFs were consistent with IAI (three or four biomarkers present). IAI (by SELDI-TOF mass spectrometry) was associated with increased HNP1-3 and Cal-C measured by ELISA. However, immunoassays detected Cal-A in only 4 of the AFs even though its specific SELDI-TOF mass spectrometry peak was identified in 19/48 AFs. Calprotectin immunoreactivity was decreased in AFs retrieved from women with IAI (P = 0.01). In conclusion, IAI is associated with increased HNP1-3 levels. In the absence of isoform-specific ELISAs, mass spectrometry remains the only way to discriminate the HNP biomarker isoforms. Monomeric Cal-A is not reliably estimated by specific ELISA as it binds to Cal-B to form the calprotectin complex. Cal-C was reliably measured by SELDI-TOF mass spectrometry or specific ELISA.<<
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