An indirect solid-phase microradioimmunoassay for human IgM-anti-IgG (rheumatoid factor)

Area of Science:

• Immunology
• Clinical Chemistry
• Biochemistry

Background:

• Rheumatoid factor (RF) is a key biomarker in autoimmune diseases like rheumatoid arthritis.
• Current latex agglutination tests for RF lack the precision required for accurate diagnosis and research.
• A need exists for a more sensitive and specific RF detection method.

Purpose of the Study:

• To develop and optimize a rapid indirect solid phase micro radioimmunoassay for quantifying serum rheumatoid factor (RF).
• To enhance the sensitivity, specificity, and reproducibility of RF measurements compared to existing methods.

Main Methods:

• Developed a micro radioimmunoassay utilizing human IgG immobilized on microtiter plates.
• Employed IgM-anti-IgG (RF) binding and detected with 125I-labelled goat anti-human IgM (125I-AHIgM).
• Optimized reagent concentrations, temperatures, and incubation times for assay performance.

Main Results:

• Achieved within-day and between-day coefficients of variation of 9% and 15%, respectively.
• Demonstrated superior precision and reproducibility compared to the standard latex test.
• Validated the assay using 100 human serum samples, showing good correlation with latex test results.

Conclusions:

• The developed radioimmunoassay provides a precise and reproducible method for serum RF quantification.
• This assay offers significant advantages over latex tests for RF determination.
• The method is valuable for both the diagnosis of RF-associated conditions and for research purposes.