DESTRUCTION OF EPIDERMAL CELLS IN VITRO BY AUTOLOGOUS SERUM FROM NORMAL ANIMALS

Sera and plasma from normal rats and rabbits were shown to be extremely toxic in vitro to autologous epidermal cells. On the other hand, mouse sera and newborn rat sera were innocuous to autologous epidermal cells. Viability of cells was assessed by the method of eosin dye exclusion upon 2 hour incubation at 37°C. Testicular cells were also killed by autologous sera, but polymorphonuclear leukocytes, lymphocytes, and lymph node cells were not affected. Autotoxicity of sera could be destroyed by the depletion of complement components with an antigen-antibody precipitate, heat, zymosan, and NH₃. Moreover, activity of sera could be absorbed out by epidermal cells, though not by lymph node cells or erythrocytes. Such absorption of toxicity was not individual-specific since homologous epidermal cells also absorbed toxicity, and in addition, were killed by fresh normal serum. Enzyme inhibitors such as soybean trypsin inhibitor and ε-amino-n-caproic acid did not affect the activity of fresh autologous serum. It is suggested that a natural barrier exists between the basal cells of the epidermis and the plasma which prevents the autodestructive process under normal conditions. Any injury to this barrier may than lead to necrosis and death of the epidermis as seen in various pathological conditions.