Proteomic but not enzyme-linked immunosorbent assay technology detects amniotic fluid monomeric calgranulins from their complexed calprotectin form.
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.
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, USA. irina.buhimschi@yale.edu
Irina A
IA
Buhimschi
Catalin S
CS
Buhimschi
Carl P
CP
Weiner
Tatsuji
T
Kimura
Benjamin D
BD
Hamar
Anna K
AK
Sfakianaki
Errol R
ER
Norwitz
Edmund F
EF
Funai
Elena
E
Ratner
D000653:Amniotic Fluid / Q000378:metabolism*; D015415:Biomarkers / Q000032:analysis; D040502:Calgranulin B / Q000032:analysis*; D002821:Chorioamnionitis / Q000378:metabolism*; D023082:Defensins / Q000032:analysis; D005260:Female; D006801:Humans; D013058:Mass Spectrometry; D011247:Pregnancy; D040901:Proteomics / Q000379:methods; D012680:Sensitivity and Specificity
D015415:Biomarkers; D040502:Calgranulin B; D023082:Defensins