Rheumatoid Factor and Its Interference with Cytokine Measurements: Problems and Solutions

Table 1

RF concentrations in the plasma samples prior to and following precipitation in patients 1–5 (P1–5). P1 is RF-negative, the rest are RF-positive.

Plasma sample	RFs prior to precipitation IU/mL	RFs following precipitation IU/mL
P1	4	5
P2	25	12
P3	195	85
P4	236	118
P5	1141	631