Objective. Rheumatoid arthritis (RA) is characterized by inflammatory reactions in joints and adjacent tissues unaccompanied by clinically evident changes in lymphatics and lymph nodes draining the inflamed areas. The explanation for this phenomenon, which contrasts with infectious processes in joints and soft tissues that evoke major changes in the lymphatic system, is unclear. To determine which inflammatory factors produced in the joints of RA patients are transported in lymph to lymph nodes, we measured levels of immunoglobulins, cytokines, and chemokines in prenodal lymph from the foot joints of RA patients and quantified their rate of transport to regional lymph nodes.Methods. Lymph was collected from the cannulated lymphatics draining the foot joints, tendons, fascia, and skin of 20 RA patients. Lymph flow rate and concentrations of proteins and immunoglobulins were measured. Cytokine and chemokine levels were quantified by enzyme-linked immunosorbent assays. Results were compared with those obtained in 20 control subjects.Results. In the cannulated vessel, the mean ؎ SEM lymph flow rate in RA patients was almost 2-fold that in control subjects (22.6 ؎ 3.2 ml/24 hours versus 13.2 ؎ 1.1 ml/24 hours; P < 0.01). Lymph concentrations of total protein, IgG, and IgM were 1.80 ؎ 0.14 gm/dl, 384 ؎ 45 mg/dl, and 32.0 ؎ 1.5 mg/dl, respectively, in RA patients and 1.66 ؎ 0.14 gm/dl, 238 ؎ 32 mg/dl, and 15.0 ؎ Conclusion. High lymph concentrations of cyto-