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Non-specific count subtraction in radioimmunoassay (a criticism)
La Ricerca in Clinica E in Laboratorio
|October 1, 1978
Summary
The radioimmunoassay (RIA) blank value does not accurately reflect nonspecific radioactivity. Subtracting this blank value from RIA results leads to analytical errors, as demonstrated by Gastrin-RIA studies.
Area of Science:
- Immunology
- Analytical Chemistry
- Biochemistry
Background:
- Radioimmunoassay (RIA) blank values are classically determined but may not accurately represent nonspecific radioactivity.
- The composition of blank tubes differs significantly from standard and unknown tubes in RIA assays.
Purpose of the Study:
- To provide evidence that subtracting the blank value (Blk) from RIA results is analytically incorrect.
- To evaluate the impact of the blank subtraction procedure on RIA data accuracy using Gastrin-RIA as a model.
Main Methods:
- Gastrin-RIA with charcoal adsorption for bound-free separation was used.
- Antigen-recovery and parallelism (serum dilution) tests were performed.
- Results from blank subtraction (BS) values were compared with non-blank subtraction (BNS) values.
Main Results:
- Blank subtraction (BS) values in recovery tests were higher than expected, unlike quantitative non-blank subtraction (BNS) values.
- Serum dilution tests showed BNS values yielded curves more parallel to the BNS standard curve than BS values did to the BS standard curve.
Conclusions:
- The classical blank subtraction procedure in RIA is analytically incorrect and should be avoided.
- Accurate RIA data processing requires omitting the empirical blank value subtraction.