Nineteen patients with psoriasis vulgaris and no other cause for syste
mic complement activation were studied for evidence of such activation
. There was a marked elevation in serum C5b-9 complexes with no other
significant complement abnormalities, and no correlation between C5b-9
levels and disease activity. This is the most detailed study of compl
ement in psoriasis yet attempted and confirms that complement activati
on is a feature of psoriasis vulgaris.