Natural killer cell activity of peripheral blood mononuclear cells from patients with various forms of systemic scleroderma.

Peripheral blood mononuclear cells from 63 patients with systemic scleroderma, including incipient or prodromal acrosclerosis, and from 20 healthy individuals were tested for natural killer (NK) cell activity and antibody-dependent cell cytotoxicity in a 4 h 51Cr release assay using K562 and L1210 cell lines respectively. In patients with systemic scleroderma natural killer cell activity was significantly decreased compared with the controls. NK cell activity was markedly lowered in patients with diffuse scleroderma and in transitional form acrosclerosis-diffuse scleroderma, and was normal in cases of acrosclerosis and/or CREST syndrome and in cases of prodromal or incipient scleroderma. Antibody-dependent cell cytotoxicity of mononuclear cells from the systemic scleroderma patients was within the normal range. The lowered natural killer cell activity correlated with the severity of systemic scleroderma, in terms of the extent of skin and organ involvement.