[Cleavage fragments of C3 and of dermo-epidermal junction of normal human skin]

Abstract

Recently, we have demonstrated the presence of C3dg deposits, a cleavage fragment of the third component of complement, on the basement membrane zone (MB) of normal human skin. These C3dg deposits are specific, isolated and not restricted to stratified squamous epithelia. Their origin is not thought to be due to passive incorporation of circulating C3dg within selected MB. Conversely, human keratinocytes are able to synthesize and secrete C3 and could represent a local source for these C3dg deposits. In situ production of C3 by epidermal cells could play a role in local inflammatory reactions. Similarly, a C3dg binding site(s) in selected basement membrane may account for the accumulation of C3-containing immune complexes in such tissues in pathological conditions.