INCREASED LEVELS OF GRANULOCYTE-SPECIFIC GLYCOSPHINGOLIPIDS IN PRETERM LABOR AMNIOTIC-FLUID

In a recent study, Hallman et al. reported high levels of lactosyl cer amide in amniotic fluid from preterm labor and postulated that this gl ycosphingolipid is of leukocytic origin. However, lactosyl ceramide is an ubiquitous glycosphingolipid also present in other cell types. In this study, the concentration of the granulocyte-specific glycosphingo lipids, paragloboside and sialyl paragloboside in term and preterm amn iotic fluids, was monitored by HPTLC-immunostaining using monoclonal a ntibodies E5C2 and 534F8, repectively. Amniotic fluid samples were obt ained by transabdominal amniocentesis for clinical indications and div ided in preterm not in labor (n = 18); preterm labor (n = 20); term no t in labor (n = 20); and term labor (n = 16). The gestational age rang ed from 25 to 41 weeks and preterm was defined as less than 37 weeks g estation. Diabetic patients were excluded from this study and none of the patients had clinical signs or symptoms of chorioamnionitis. Sampl es with macroscopic blood contamination were also excluded. The sample s from each group were pooled, lyophilized, the residues extracted wit h chloroform-methanol-water (C-M-W, v/v/v), and the glycosphingolipid fraction isolated by a combination of peracetylation with pyridine-ace tic anhydride, Florisil column chromatography, and deacetylation with sodium methoxide. Aliquots of the purified glycosphingolipid fraction were streaked onto either Whatman HP-K or Merck aluminum-backed silica gel plates for high performance thin layer chromatographic analysis ( HPTLC), following reaction with the orcinol-ferric chloride reagent; o r HPTLC-immunostaining following reaction with anti-paragloboside and anti-sialyl paragloboside monoclonal antibodies E5C2 and 534F8, respec tively. Preterm labor amniotic fluid contained significantly higher co ncentrations of the granulocyte-specific glycosphingolipids lactosyl c eramide, paragloboside and sialyl paragloboside as compared to term la bor amniotic fluid. Preterm and term amniotic fluids with no labor had low to undetectable levels of these glycosphingolipids. These results confirm the findings reported by Hallman et al. and provide additiona l evidence that supports the hypothesis that the onset of preterm labo r may be associated with subclinical infection.