Serum aminoterminal propeptide of type III procollagen in systemic sclerosis. A follow-up--investigations in subclasses and during therapy.

Fifty-seven patients with systemic sclerosis were investigated for connective tissue turn-over related to type III collagen. Sera from 13 patients with diffuse cutaneous systemic sclerosis and 44 patients with limited cutaneous systemic sclerosis were analysed for aminoterminal propeptide of type III procollagen (PIIINP) by a radioimmunoassay based on human propeptide. Increased levels of PIIINP in serum correlated with skin involvement and the clinical course. All patients with diffuse cutaneous systemic sclerosis had levels above the normal range, and in limited cutaneous systemic sclerosis elevated PIIINP levels seemed to be correlated with rapid progression and with extension of lesions. Immunosuppressive drugs, cyclosporin A, and prednisone with or without cyclophosphamide, which were given to patients with rapid disease progression, significantly reduced PIIINP. This was also the case with penicillamine, but to a lesser degree. Our data support the suggestion that immunosuppressive agents are justified in rapidly progressive, life-threatening or disabling disease, when used with the necessary precautions. Serum PIIINP may be utilized as a marker of type III collagen fibrogenesis in systemic sclerosis and be of prognostic value. PIIINP may also be of use in the differential diagnosis between diffuse cutaneous systemic sclerosis and scleredema.