Lactoferrin in synovial fluid.

The synovial lactoferrin (LF) concentrations of 59 patients with active rheumatoid arthritis were determined. The median value of LF was 4.64+/-3.59 mg/100 ml, but in degenerative arthropathy the levels of the metal-protein were much lower and often not titratable. These variations in the LF concentration explain the low blood-iron levels in inflammatory states, even when the concentration of the metal-protein is not statistically correlated in inflammatory tests, IgG, complement fractions (of the normal or alternate pathway), or variations of other protein fractions of leucocyte origin.