Variability in follicular fluid high density lipoprotein particle components measured in ipsilateral follicles

Abstract

Purpose: The purpose of this study was to examine the biological variability of follicular fluid (FF) high density lipoprotein (HDL) particle components measured in ipsilateral ovarian follicles.

Methods: We collected FF from two ipsilateral follicles among six women undergoing in vitro fertilization (IVF). We measured concentrations of 19 FF HDL particle components, including HDL cholesterol, free cholesterol, four cholesteryl esters, phospholipids, triglycerides, paraoxonase and arylesterase activities, apolipoproteins A-1 and A-2 (ApoA-1 and ApoA-2), and seven lipophilic micronutrients, by automated analysis and with high-performance liquid chromatography. We assessed biological variability using two-stage nested analysis of variance and compared values with those previously published for contralateral follicles.

Results: For most FF HDL analytes, there was little variability between follicles relative to the variability between women (i.e., %σ(2) F:%σ(2) B <0.5). Intraclass correlation coefficients were >0.80 for HDL cholesterol (0.82), phospholipids (0.89), paraoxonase (0.96), and arylesterase (0.91) activities, ApoA-1 (0.89), and ApoA-2 (0.90), and single specimen collections were required to estimate the subject-specific mean, demonstrating sufficient reliability for use as biomarkers of the follicular microenvironment in epidemiologic and clinical studies.

Conclusions: These preliminary results raise the possibility for tighter regulation of HDL in follicles within the same ovary vs. between ovaries. Thus, collection of a single FF specimen may be sufficient to estimate HDL particle components concentrations within a single ovary. However, our results should be interpreted with caution as the analysis was based on a small sample.

Keywords: Biological variability; Follicular fluid (FF); High density lipoprotein (HDL); Human ovarian follicles; In vitro fertilization (IVF).

Fig. 1

Sampling strategy for the measurement of follicular fluid (FF) high density lipoprotein (HDL) analytes measured in ipsilateral follicles, collected from in vitro fertilization patients. Group I analytes included HDL cholesterol, phospholipids, triglycerides, arylesterase, and paraoxonase activities, and apolipoproteins (ApoA-1 and ApoA-2), for which two determinations were made per sampled follicle. Group II analytes included free cholesterol, cholesteryl palmitate, cholesteryl oleate, cholesteryl linoleate, cholesteryl arachidonate, retinol, β-carotene, β-cryptoxanthin, α-tocopherol, γ-tocopherol, lutein/zeaxanthin, and lycopene, for which one determination was made per sampled follicle

Fig. 2

Intraclass correlation coefficients (ICCs) with 95 % confidence intervals for follicular fluid high density lipoprotein (HDL) particle components measured in specimens collected from ipsilateral (−I) and contralateral ovaries (−C). a Group I HDL analytes include HDL cholesterol, phospholipids, triglycerides, arylesterase, and paraoxonase activities, and apolipoproteins (ApoA-1 and ApoA-2), and b group II HDL analytes include free cholesterol, cholesteryl palmitate, cholesteryl oleate, cholesteryl linoleate, cholesteryl arachidonate, retinol, β-carotene, β-cryptoxanthin, α-tocopherol, γ-tocopherol, lutein/zeaxanthin, and lycopene