Effect of plasma interference on different vasopressin antisera

Area of Science:

• Endocrinology
• Assay Development
• Analytical Chemistry

Background:

• Accurate measurement of arginine vasopressin (AVP) is crucial for diagnosing and managing fluid balance disorders.
• Plasma interference in radioimmunoassays can lead to inaccurate AVP concentration values.
• High-affinity and specific antisera are essential for reliable AVP detection.

Purpose of the Study:

• To investigate the impact of plasma interference on two different AVP antisera.
• To compare the specificity and accuracy of antibody A and antibody B in AVP radioimmunoassay.
• To identify AVP antisera that minimize plasma interference for improved diagnostic accuracy.

Main Methods:

• Chromatography of plasma from normal subjects and patients with cranial diabetes insipidus using Sephadex G-25.
• Analysis of eluted fractions using two distinct AVP antisera (antibody A and antibody B).
• Plasma extraction using Florisil to assess its effect on reducing interfering substances.

Main Results:

• Antibody A detected significant AVP-like material in the void volume (95% more than antibody B), indicating substantial interference.
• Similar elution profiles were observed in normal and diabetic subjects, with the third peak absent in the diabetic patient.
• Florisil extraction reduced interfering peaks for antibody A and eliminated the void volume peak for antibody B.

Conclusions:

• Plasma interference significantly affects the absolute quantification of AVP in radioimmunoassays.
• Antibody B exhibits higher specificity and less susceptibility to plasma interference compared to antibody A.
• AVP antisera demonstrating minimal plasma interference are recommended for accurate AVP radioimmunoassay.