Menstrual- and gender-dependent variations in circulating IL-1 agonists, antagonists, and binding proteins

Area of Science:

• Immunology
• Endocrinology
• Biochemistry

Background:

• Interleukin-1beta (IL-1beta) plays a crucial role in inflammatory processes.
• Circulating binding proteins can influence the measurement and biological activity of cytokines.
• Sex-related differences in immune responses are increasingly recognized.

Purpose of the Study:

• To investigate sex-related differences in plasma binding proteins for IL-1beta.
• To determine the impact of these binding proteins on immunoassays for IL-1beta and IL-1 receptor antagonist (IL-1Ra).
• To identify specific binding proteins involved in IL-1beta complexation.

Main Methods:

• Radioligand binding assay using 125I-labeled IL-1beta.
• Chromatographic separation of plasma samples to quantify bound and free IL-1beta.
• Measurement of plasma soluble IL-1 receptor type II (sIL-1RII) concentrations.
• Comparison of plasma IL-1beta and IL-1Ra immunoreactivity with cellular secretion rates.

Main Results:

• Significant differences in IL-1beta binding capacity were observed between men and women (P = 0.032).
• Plasma IL-1beta binding correlated with sIL-1RII concentrations (r = 0.647, P = 0.007).
• Plasma IL-1beta immunoreactivity did not accurately reflect cellular secretion rates due to assay interference by sIL-1RII.

Conclusions:

• Plasma IL-1beta binding capacity exhibits sex-related differences.
• Soluble IL-1 receptor type II (sIL-1RII) is a major factor contributing to IL-1beta binding in plasma.
• Assay results for IL-1beta and IL-1Ra in plasma may be affected by binding proteins, necessitating careful interpretation.