Practicable enzyme immunoassay for neuron-specific enolase in human serum

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Background:

• Neuron-specific enolase (NSE) is a biomarker for neuroendocrine tumors, particularly small-cell lung carcinoma.
• Accurate and sensitive measurement of serum NSE is crucial for diagnosis and monitoring.

Purpose of the Study:

• To develop a practical and sensitive sandwich-type enzyme immunoassay for quantifying neuron-specific enolase (NSE) in human serum.
• To validate the assay's performance characteristics, including sensitivity, specificity, and reproducibility.

Main Methods:

• A sandwich enzyme immunoassay was established using polystyrene balls with immobilized antibody F(ab')2 fragments.
• Antibody Fab' fragments labeled with beta-D-galactosidase from Escherichia coli were employed.
• The assay utilized purified antibodies specific to bovine neuron-specific gamma-enolase.

Main Results:

• The developed assay demonstrated a minimum detectable sensitivity of 50 pg per assay tube (1 microgram/L of NSE).
• The assay showed no cross-reactivity with alpha-enolase or beta-enolase, indicating high specificity.
• Intra-assay and inter-assay coefficients of variation were less than 10%, signifying good reproducibility.
• Serum NSE values correlated well (r = 0.96) with a previously developed method.
• Elevated NSE levels were observed in patients with small-cell lung carcinoma compared to healthy subjects.

Conclusions:

• The developed sandwich enzyme immunoassay is a practical, sensitive, and specific method for serum NSE determination.
• This assay can be performed within a working day and shows potential for clinical application in diagnosing small-cell lung carcinoma.