Excess plasma proteins as a cause of chronic inflammation and lymphodema: quantitative electron microscopy.

The subcutaneous tissue of rats was injected with plasma. PVP, or saline. In spite of precautions to avoid immunological reactions and the release of mediators, it was found that the plasma-injected animals had many of the signs of chronic inflammation-even at 64 days. These were considerably reduced by coumarin, a benzo-pyrone, which is known to enhance the lysis of proteins by macrophages. The numbers of these cells were greatly increased in the injection site-especially with the administration of coumarin. PVP also moderately increased macrophage numbers, but did not cause the increase in fibroblast numbers or collagen formation associated with plasma-injections. It is concluded that altered proteins in the tissues are a cause of chronic inflammation and that, in particular, chronic lymphoedema is a form of chronic inflammation.