Development of a novel immunoassay for the assessment of plasma Gas6 concentrations and their variation with hormonal status.
BACKGROUND
Gas6 is a vitamin K-dependent antiapoptotic protein that has been implicated in cardiovascular pathophysiology. We report the development and validation of an ELISA for Gas6, and the variation of plasma Gas6 with hormonal status in a study designed to evaluate the effect of oral contraception on plasma markers.


METHODS
After validation of the main stages of the ELISA assay, we measured plasma Gas6 concentrations in 94 male and 88 female healthy volunteers ages 18 to 38 years. Forty-five of the women then received an oral contraceptive, which contained ethinylestradiol and levonorgestrel, for 3 months before a new measurement was performed at the same time point in their menstrual cycles.


RESULTS
Interassay imprecision was 5.8%-11.8%, and the detection limit was 5.9 microg/L. Mean Gas6 plasma concentrations were significantly lower in men (52.0 microg/L) than in women not receiving oral contraceptives (63.8 microg/L, P <0.001). In the women who received oral contraceptives, Gas6 concentrations decreased after 3 months of therapy from 63.6 microg/L to 51.9 microg/L (P <0.001).


CONCLUSIONS
We have developed a simple and reproducible ELISA assay for measuring plasma Gas6 concentrations, which vary with sex and are decreased by oral contraceptive use. These results suggest regulation of plasma Gas6 concentrations by sex hormones. Future clinical studies may require participants to be stratified by sex.
Clauser
Sylvain
S
Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service d'Hématologie Biologique A, Paris, France.
Peyrard
Séverine
S
Gaussem
Pascale
P
Crespin
Malvina
M
Emmerich
Joseph
J
Aiach
Martine
M
Borgel
Delphine
D
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D003277:Contraceptives, Oral, Combined; D003278:Contraceptives, Oral, Hormonal; D004797:Enzyme-Linked Immunosorbent Assay; D004997:Ethinyl Estradiol; D005260:Female; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D016912:Levonorgestrel; D008297:Male; D010949:Plasma; D012016:Reference Values; D012680:Sensitivity and Specificity; D012737:Sex Factors; D000099255:Growth Arrest-Specific Protein 6
D015415:Biomarkers; D003277:Contraceptives, Oral, Combined; D003278:Contraceptives, Oral, Hormonal; D004997:Ethinyl Estradiol; D012739:Gonadal Steroid Hormones; D036341:Intercellular Signaling Peptides and Proteins; D016912:Levonorgestrel; D000099255:Growth Arrest-Specific Protein 6