Activated, cytotoxic lymphocytes in systemic vasculitis.

Peripheral blood lymphocytes from some patients with rheumatoid vasculitis and giant cell arteritis were cytotoxic in vitro towards endothelial cells, but not fibroblasts. Use of cell surface markers and cell density showed that cytotoxicity correlated with numbers of HLA-DR bearing cells, but not with cells bearing CD3, the transferrin receptor, or less dense lymphocytes. We concluded that activated, cytotoxic lymphocytes were present in the peripheral blood of a sub-set of patients with vasculitis.