The effect of coumarin (5,6 benzo-α-pyrone) on elicited members of the mononuclear system in dogs with chronic secondary lymphedema

The effect of coumarin is investigated on the morphological features of members of the mononuclear phagocytic system (MPS) attaching to subcutaneously (s.c.) implanted coverslips in "normal" and chronically lymphedematous tissues. In untreated "normal" tissues there was no attachment suggesting that the presence of lymphedema elsewhere influences MPS activity. Coumarin restored attachment proportions to those found in normal tissues of dogs with no lymphedema. In lymphedema, coumarin significantly increased the proportion of macrophages which were round with less than ten pseudopods (new recruits) and the proportion with distinct pseudopods combined with more than ten vacuoles (active elicited members of the MPS). Coumarin resulted in a significant decline in the proportion of macrophages which were round and with more than ten apparently lipid-containing vacuoles, suggesting a facilitation of their removal to other sites.