Activated complement fragments: Deposition and function on cellular targets

These data were obtained from quantitative analysis of immunoglobulin G (IgG) antibody-mediated classical pathway activation on mammalian cells (melanoma cell line). Normal human serum was used as the source of complement, along with saturating amounts of human antibody to the cell line. Similar data have been obtained on bacterial membranes, although relative numbers were less (approximately a log) corresponding to reduced surface area and antigenic density. The complement system is the "guardian of the intravascular space." It is designed to attack bacteria attempting to enter the intravascular space.