Immunobiological aspects of Clq in sera of patients with cutaneous vasculitis and collagen diseases.

Clq was comparatively quantified with CH50 or C3 in sera of patients with various types of cutaneous vasculitis and collagen diseases. The following results were found: 1) Elevated levels of Clq were seen much more frequently in cutaneous vasculitis and PSS. 2) No significant correlations were found between Clq and CH50 or C3, except for a moderate rank correlation between Clq and C3 in SLE. 3) The amount of hydroxyproline in serum (collagen-like protein) is nearly identical with the calculated value of that present in Clq.