Effect of preincubation of histone coated ELISA wells with aggregated normal IgG on the binding of IgM rheumatoid factor from rheumatoid arthritis (RA) serum samples. Reaction (net A450) from 10 RA serum samples with histone coated wells and histone coated wells preincubated with heated normal serum; enzyme-conjugate is rabbit antihuman IgM (Fc5μ)-horse radish peroxidase. Values are mean (SD)
| RA specimen number | Histone coated wells | Histone coated wells and heated normal serum |
| R1 | 0.420 (0.017) | 1.801 (0.035) |
| R2 | 0.173 (0.009) | 1.779 (0.045) |
| R3 | 0.138 (0.020) | 1.818 (0.075) |
| R4 | 0.583 (0.025) | 1.245 (0.050) |
| R5 | 0.338 (0.015) | 1.960 (0.032) |
| R6 | 0.275 (0.028) | 1.616 (0.040) |
| R7 | 0.689 (0.035) | 1.974 (0.014) |
| R8 | 0.102 (0.011) | 2.100 (0.045) |
| R9 | 0.150 (0.017) | 1.904 (0.050) |
| R10 | 0.214 (0.008) | 1.249 (0.020) |