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

Table 2

RF concentrations in synovial fluid prior to and following precipitation in patients SF1–SF5. SF1 was RF-negative, SF2–SF5 were RF-positive.

Synovial fluid sample	RFs prior to precipitation IU/mL	RFs following precipitation IU/mL	RFs in plasma from the same patient IU/mL
SF1	2	1	7
SF2	34	1	85
SF3	29	13	78
SF4	54	15	54
SF5	189	60	400