Killing of human dermal capillary endothelial cells by antibody-dependent cellular cytotoxicity

Damage to the microvasculature occurs commonly in autoimmune diseases affecting the skin. There has been little investigation of immune mechanisms other than immune complex deposition as a major cause of microvascular damage. We have investigated the potential of antibody-dependent cellular cytotoxicity (ADCC) to cause vascular destruction in an in vitro model consisting of human dermal microvascular endothelial cells to which were added antibody and leukocytes. Severe damage was induced by antibody and lymphocytes. Monocytes or neutrophils were not able to mediate cytotoxicity although activated neutrophils caused endothelial detachment. The cytotoxic cells were OKT3-, Leu 11+ and were identified as K cells. ADCC was not inhibited by human serum or aggregated IgG. These results imply that ADCC may have a role in causing the vascular destruction observed in some human autoimmune skin diseases.