Human umbilical cord vein smooth muscle cells lack receptors for C3b and the Fc portion of immunoglobulin G.

Under apparently normal conditions, the smooth muscle cells obtained from veins of human umbilical cord do not possess receptors for C3b or the Fc portion of IgG. These receptors were not expressed even after exposure to neutrophil lysate or a superoxide-generating system. The lack of these receptors argues against the possibility that smooth muscle cells participate in the pathogenesis of immune complex diseases through binding of C3b or Fc fragments.