Crithidia luciliae assay for antibodies to native DNA in procainamide-induced lupus erythematosus.

Sera from 49 patients with procainamide-induced lupus erythematosus or circulating antinuclear antibodies were found to be negative for antibodies to native DNA by the CL immunofluorescence assay. This finding suggests that the CL assay is helpful in discriminating between procainamide-induced and naturally occurring systemic lupus erythematosus. The results further confirm the relatively high degree of specificity of the CL assay for SLE.

Skin thickness and collagen content in progressive systemic sclerosis and localized scleroderma.

Skin biopsies of uniform location and surface area (7 mm diameter) were obtained from the extensor aspect of the forearm of 147 patients with progressive systemic sclerosis (PSS) (107 with diffuse scleroderma, 40 with the CREST syndrome variant) and 58 individuals with normal skin. After careful removal of all subcutaneous fatty tissue, the skin cores were weighed and their water and hydroxyproline content determined. Despite recent claims to the contrary, it was found that there is a marked and highly significant increase in the thickness of the skin during the indurative phase of PSS, and that this is associated with a proportionate increase in total dermal collagen content.