Clq AND C3bi BINDING ACTIVITIES OF THE COMPONENTS OF A PLASMIN-TREATED HUMAN IMMUNOGLOBULIN PREPARATION

抄録

Each of the three major components isolated from a commercial plasmin-treated human immunoglobulin preparation, namely, the plasmin-resistant 7S IgG fraction (PRG), Fab fragment and Fc fragment, was tested before and after heat treatment for binding Clq and fixing C3bi. In unheated state, only PRG was found to bind Clq, whereas none bound C3bi. The binding of Clq by PRG was enhanced by heat treatment which also conferred the activity of binding C3bi to PRG and to Fc fractions. From these results, anticomplementary activity of unheated PRG fraction seems to be due mainly to the complement activation via the classical pathway, whereas the activation by the heat-treated Fc fragment might be via an alternative pathway.