In vitro autoreactivity against autologous keratinocytes in patients with rheumatoid and juvenile idiopathic arthritis

In patients with rheumatoid arthritis or juvenile idiopathic arthritis we observed the tendency of peripheral blood mononuclear cells to induce graft versus host disease like histhopathological changes of grade II or above (evaluated according to standard Lerner's classification) when co-cultured in vitro with autologous skin explants. The aim of this study was to verify if observed skin damage was really of an autoimmune origin and we also tried to compare results with autoreactivity directed against autologous synovium. We suppose that humoral as well as cellular autodestructive mechanisms may be involved in the pathogenesis of observed skin damage.

Methods

To prove this hypothesis (cellular autodestruction)we used 51Cr release cytotoxic test where peripheral blood mononuclear cells were co-cultured with autologous synovial cells as well as with autologous keratinocytes.

Results

We found that patient's peripheral blood mononuclear cells lysed both autologous keratinocytes (specific lysis 60%) as well as autologous synovial cells (59% specific lysis). No specific lysis of autologous keratinocytes and synovial cells was observed in healthy controls.

We suppose that peripheral blood mononuclear cells might recognise similar autoantigen(s) expressed on epidermal cells that might give rise an autoimmune response in synovium.