Quantitation of spreading factor in human biologic fluids.

Area of Science:

• Biochemistry
• Cell Biology
• Immunology

Background:

• Spreading factor (SF) is a glycoprotein found in human plasma and serum.
• SF influences mammalian cell attachment, spreading, proliferation, and differentiation in vitro.
• Quantifying SF levels is crucial for understanding its biological roles.

Purpose of the Study:

• To develop and utilize an immunoassay for quantifying Spreading Factor (SF) levels.
• To measure SF concentrations in human plasma, serum, amniotic fluid, and urinary protein.
• To compare SF levels across different physiological and developmental stages.

Main Methods:

• Development of a monoclonal antibody specific to Spreading Factor (SF).
• Utilization of a purified SF reference standard for immunoassay calibration.
• Quantification of SF using the immunoassay in human plasma, serum, amniotic fluid, and urinary protein samples.

Main Results:

• SF levels in adult plasma averaged 4 µg/mg of plasma protein (range: 2.5–7 µg/mg).
• SF concentrations did not significantly differ between adults, fetuses, infants, children, or adolescents.
• SF levels in amniotic fluid (12–23 weeks gestation) were comparable to adult serum levels.
• Urinary protein exhibited a specific activity of 10.9 µg SF/mg protein.

Conclusions:

• The developed immunoassay accurately quantifies SF in various human biological fluids.
• SF levels are relatively consistent across different age groups from fetus to adult.
• SF is present in amniotic fluid and urine, suggesting potential roles in fetal development and excretion.