Localized monocyte chemotactic protein-1 production correlates with T cell infiltration of synovium in patients with psoriatic arthritis.

OBJECTIVE

To examine normal and psoriatic skin and synovial tissue from patients with psoriatic arthritis (PsA) for evidence of monocyte chemotactic protein-1 (MCP-1) mediated T cell chemotaxis.

METHODS

Peripheral blood (PB), synovial fluid (SF), normal and psoriatic skin, and synovial biopsies were obtained from patients with PsA (n = 19) and compared to samples from normal (n = 5) and disease (n = 5) controls (NC, DC). Immune cell populations in PB and SF samples were assessed by immunofluorescent labeling and flow cytometry, levels of soluble MCP-1 were determined by quantitative ELISA, and immunohistochemistry was used to detect T cell subsets and macrophages and MCP-1 protein in frozen skin and synovial tissue sections.

RESULTS

CD8+ but not CD4+ T cells were elevated in SF compared to PB, and the majority of these cells expressed CD45RO. Plasma MCP-1 levels in PsA were elevated relative to NC. MCP-1 levels were significantly higher than paired plasma samples in patients with recent onset (< 6 mo) synovitis (n = 10). A positive correlation was observed between synovial T cell numbers and MCP-1 levels in SF. MCP-1 protein was present in all tissues examined, but most intense expression was observed in synovium.

CONCLUSION

Elevated concentrations of MCP-1 concomitant with memory T cell infiltration in PsA SF suggests that MCP-1 mediated chemotaxis is involved in the recruitment of T lymphocytes into the synovial compartment of patients with PsA.