Complement changes during granulocyte adhesion

The granulocyte adherence assay was investigated as a potential in vitro model of filtration leukapheresis to study the effects produced on the complement system by passing anticoagulated blood through columns packed with nylon fibers. Complement activation per se was found not to be a prerequisite for the simple attachment of neutrophils to nylon fibers in this system, because none of the complement components studied were consumed in blood freely flowing through or incubated within adherence columns. Moreover, concentrations of the B antigenic determinant of C3 were unchanged, an indication that this pivotal component had not been cleaved. Although not required for adherence, complement activation is probably initiated by the process of neutrophil attachment, because chemotactic activity was generated. The precise nature of this activity was not identified, but information from previous studies of filtration leukapheresis and granulocyte adherence suggests the possibility of complement origin.