Digoxinlike immunoreactive factor isolated from human pleural fluid is structurally similar to digoxin

Area of Science:

• Biochemistry
• Cardiology
• Analytical Chemistry

Background:

• Human endogenous digoxin-like immunoreactive factors (DLIF) are substances that mimic the effects of digoxin.
• Previous research suggested a structural relationship between DLIF and cardiac glycosides.
• The presence and precise chemical structure of DLIF in various human tissues remained to be fully elucidated.

Purpose of the Study:

• To chemically characterize human endogenous digoxin-like immunoreactive factors (DLIF).
• To determine if DLIF is present in human pleural effusions.
• To compare the chromatographic profile of DLIF with known cardiac glycosides.

Main Methods:

• Radioimmunoassay was used to detect DLIF activity in human pleural effusions.
• Ion exchange chromatography was employed for DLIF extraction and concentration.
• Reverse-phase high-performance liquid chromatography (RP-HPLC) was utilized for separation and purification.
• Cochromatography with radioactively labeled glycosides was performed to compare DLIF with digoxin.

Main Results:

• DLIF activity was detected in pleural fluid from four patients, with an average concentration of 0.35 ng/mL.
• RP-HPLC analysis revealed a single peak of DLIF activity.
• Cochromatography demonstrated that DLIF is chromatographically identical to digoxin.
• This study provides the first evidence of DLIF presence in human pleural fluids.

Conclusions:

• Human endogenous digoxin-like immunoreactive factors (DLIF) are present in pleural effusions.
• The chemical structure of DLIF is closely related to cardiac glycosides.
• DLIF is chromatographically indistinguishable from digoxin, supporting its identity as a digoxin-like substance.