Increased Abundance of Cytotoxic T Cells in Synovial Fluid of a Dog With Erosive Immune-Mediated Polyarthritis

Murakami K, Kobayashi K, Kutara K, Nakamura SI, Tagawa M, Itoi T.

Most dogs with nonerosive immune-mediated polyarthritis (IMPA) have neutrophilic inflammation in the synovial fluid. On the other hand, some dogs with erosive IMPA have increased mononuclear cells as the most abundant cell subset in the synovial fluid. A 9-year-old, neutered female miniature dachshund presented with lameness and lethargy. Physical examination revealed subluxation of the carpal and tarsal joints. Synovial fluid tests revealed an increased number of leukocytes, mainly mononuclear cells, and radiographic examination led to a diagnosis of erosive IMPA. Compared with nonerosive IMPA, flow cytometric analysis of the synovial fluid in this case showed a significant expansion of T cells-predominantly CD8+ cytotoxic T cells-while monocyte and B cell counts remained comparable. Treatment with mycophenolate mofetil reduced leukocytes in the synovial fluid and improved the dog's activity, although bone erosion slowly progressed. Based on these findings, we propose that T cells, especially cytotoxic T cells, in synovial fluid contribute to inflammation in canine erosive IMPA and may be a therapeutic target.

Case Rep Vet Med

9048633

https://onlinelibrary.wiley.com/doi/full/10.1155/crve/9048633