Are cytokines stable in frozen amniotic fluid samples?

A. Ghidint, C. Y. Spong, M. Ossandon, C. N. Walked

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: To determine if amniolic Iltud cvtokines are stable when fro/en at -70J C, the cytokine interleukin-i> OL-(>) was measured in the same sample ol mid trimester amniotic fluid one vear aparl. STUDY DESIGN: In this study, IL-6 was imnumoassayed in paired samples of amniotic fluid kept a( -70'J C. at two different time periods, one \ear apart. Inclusion criteria were: (1) samples with clearlv identifiable numbers (2) no evidence of breaks in sealing of samples, and (3) singletun gestation. Amniotic fluid was imnumoassayed for IL-6 (Quantikine, R&D System) in July 1995 and 1996 [sensitivities 1.74 and 2.37 pg/mL. interassa\ coefficients oi'variation (CV) H.9% and 2.6%, and intra-assay CV 3.5. and 1.9% respectively]. Statistical analvsis included paired t-test, Wilcoxonsigued rank, and regression with p < 0.05 significant. IL-6 values were normalized using natural log transformation for statistical analysis. RESULTS: 30 patients with paired amniolic fluid samples from 1993-1995 were immunoassayed. The values of IL-6 \veie significantly lowei in the 1996 assay compared with the 1995 a.ssav [median 230.8 (range 40.9-3711.3) v.s. 289.2 (range 53.7-19100.0) ng/mL. P < 0.001 ]. CONCLUSIONS: IL-6 values in amniotic fluid appear to decrease with lime even with optimal freezing conditions therefore the \ear of sample must be taken into consideration when evaluating amniotic fluid IL-6 levels fiom a databank of fluid. The implication ol these findings for other c\tokines requires further investigation.

Original languageEnglish (US)
Pages (from-to)S125
JournalActa Diabetologica Latina
Volume176
Issue number1 PART II
StatePublished - Dec 1 1997
Externally publishedYes

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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