Lymph draining from foot joints in rheumatoid arthritis provides insight into local cytokine and chemokine production and transport to lymph nodes

Objective. Rheumatoid arthritis (RA) is characterized by inflammatory react ions in joints and adjacent tissues unaccompanied by clinically evident cha nges in lymphatics and lymph nodes draining the inflamed areas. The explana tion for this phenomenon, which contrasts with infectious processes in join ts and soft tissues that evoke major changes in the lymphatic system, is un clear. To determine which inflammatory factors produced in the joints of RA patients are transported in lymph to lymph nodes, we measured levels of im munoglobulins, cytokines, and chemokines in prenodal lymph from the foot jo ints of RA patients and quantified their rate of transport to regional lymp h nodes. Methods. Lymph was collected from the cannulated lymphatics draining the fo ot 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 a lmost 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 <plus/minus> 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 +/- 3 2 mg/dl, and 15.0 +/- 1.3 mg/dl, respectively, in control subjects. The cor responding lymph:serum (L:S) ratios were 0.21 +/- 0.02, 0.22 +/- 0.02, and 0.15 +/- 0.02, respectively, in RA patients and 0.22 +/- 0.02, 0.19 +/- 0.0 2, and 0.11 +/- 0.02, respectively, in control subjects. The US ratios of < I and the absence of significant differences between groups suggested a la ck of local production of immunoglobulins. In RA patients, lymph concentrat ions (in pg/ml) were as follows: interleukin-1<beta> (IL-1 beta) 14.8 +/- 3 .9, IL-6 511 +/- 143, tumor necrosis factor alpha (TNF alpha) 9.9 +/- 1.1, IL-1 receptor antagonist (IL-1Ra) 4,274 +/- 737, IL-10 13.3 +/- 4.4, IL-8 8 46 +/- 174, IL-15 6.2 +/- 0.9, granulocyte-macrophage colony-stimulating fa ctor (GM-CSF) 2.30 +/- 0.15, vascular endothelial growth factor (VEGF) 80.4 +/- 8.6, and macrophage inflammatory protein 1 alpha (MIP-1 alpha) 171 +/- 34. In control subjects, these values were as follows: IL-1 beta 1.50 +/- 0.25, IL-6 79.0 +/- 14.6, TNF alpha 4.4 +/- 1.1, IL-1Ra 208 +/- 52, IL-10 0 .0, IL-8 216 +/- 83, IL-15 5.00 +/- 0.45, GM-CSF 0.40 +/- 0.05, VEGF 42.0 /- 2.4, and MIP-1 alpha 3.4 +/- 1.7 (P < 0.05 versus RA patients for all ex cept IL-15). The US ratio was >1 in all RA patient samples for IL-1 beta, I L-6, IL-1Ra, IL-8, GM-CSF, IL-10, IL-15, TNF alpha, and MIP-1 alpha, indica ting local production of cytokines. Great variability in lymph cytokine con centrations, presumably reflecting differences in the intensity of local in flammation, was not reflected in serum cytokine concentrations. Intravenous ly infused methylprednisolone decreased lymph cytokine levels to normal wit hin 12 hours. In contrast, their concentrations in serum showed little or n o change. Conclusion. High lymph concentrations of cytokines and chemokines, exceedin g those in serum, were found in RA patients. The US concentration ratios of >1 indicate the local production of these cytokines and chemokines in the inflamed tissues. High flow rates of lymph containing high cytokine concent rations through the regional lymph nodes are likely to affect node lymphocy tes and dendritic cells. Analysis of cytokines in lymph should provide insi ght into events in inflamed tissues in RA and in regional lymph nodes.