Radioimmunoassay that measures serum vitamin B12

Area of Science:

• Biochemistry
• Immunology
• Analytical Chemistry

Background:

• Serum vitamin B12 levels are crucial for diagnosing various health conditions.
• Existing methods for vitamin B12 determination may face interference from analogues and binders.

Purpose of the Study:

• To develop a specific radioimmunoassay (RIA) for routine serum vitamin B12 determination.
• To ensure the assay minimizes interference from cobalamin analogues and non-specific binders.

Main Methods:

• Raised antisera in rabbits against cyanocobalamin coupled to human serum albumin.
• Selected high-affinity antiserum (Ka = 6.7 x 10(10) L/mol) for assay development.
• Utilized magnetisable particles for separation and autoclaving to destroy serum binding capacity.

Main Results:

• Achieved high antibody titres (up to 1/188,000) and selected optimal assay parameters (tracer 22 pmol/L, antiserum dilution 1/100,000).
• Demonstrated excellent correlation with microbiological assays (100% recovery).
• Reported low cross-reactivity with dicyanide cobinamide (9.8%) and hydroxocobalamin (8.1%).

Conclusions:

• The developed immunoassay provides a specific and reliable method for serum vitamin B12 measurement.
• The assay effectively overcomes interference from cobalamin analogues and non-specific binding.
• This RIA facilitates routine clinical determination of vitamin B12 levels.