A subset of natural killer cells is greatly expanded within inflamed joints

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Arthritis Rheum 2002 Jul;46(7):1763-72

A subset of natural killer cells is greatly expanded within inflamed

joints.

Dalbeth N, Callan MF.

Weatherall Institute of Molecular Medicine, Radcliffe Hospital,

Oxford, UK.

OBJECTIVE: To determine whether natural killer (NK) cells are present

within inflamed joints and whether they might play a role in amplifying

the inflammatory process.

METHODS: Paired samples of peripheral blood and synovial fluid were

obtained from 22 patients with inflammatory arthritis. The frequency and

phenotype of the peripheral and synovial NK cells were analyzed using a

panel of monoclonal antibodies. Further experiments were performed to

investigate the functional capacity of the synovial NK cells.

RESULTS: The study showed that the CD3-, CD56(bright) subset of NK cells

was greatly expanded within inflamed joints. Our experiments suggested

that this subset of cells was preferentially recruited from the

periphery and that NK cells may be further activated by cytokines

present within the joint. Furthermore, synovial NK cells responded to a

combination of interleukin-12 (IL-12) and IL-15, cytokines that are

secreted by cells of the monocyte/macrophage lineage, by rapidly

secreting interferon-gamma, a cytokine that can, in turn, activate

macrophages.

CONCLUSION:A subset of NK cells was expanded within inflamed joints. The

functional properties of these NK cells rendered them good candidates

for a role in interacting with the macrophage/monocyte population within

the joint, thus amplifying the production of proinflammatory cytokines.

PMID: 12124859