Automated enhanced latex agglutination assay for rheumatoid factors in serum

This improved assay of rheumatoid factors in serum, described here for use with the Baker "Encore" centrifugal analyzer, is efficient, with 250-sample throughput per hour; reproducible, with between-batch CV = 5% and within-batch CV = 2% (mid-assay range); and results correlate well (r = 0.9) with those by other methods. The method is fully quantitative and automated, involves no predilution steps, and can be adapted for use in a wide range of systems. It has a sensitivity of 96% and specificity of 80% in diagnosing rheumatoid arthritis.