ABSTRACT
This chapter describes the formation of immune complexes and complement activation, and the interactions of Fibronectin (Fn) with cold-insoluble globulin (Clq), and with C3 and immunoglobulin. It summarizes the possible biologic and pathologic consequences of immune-complex-associated FN with regard to experimental findings. Thus, immune complexes, either as relatively soluble complexes or as part of cell surface complexes, will differ in their content of attached complement proteins. The question of whether Fn and Clq exhibit a binding interaction in the presence of human physiologic fluids was addressed by Carsons. If Fn has some biologic function through its interaction with immune complexes, the possible binding of Fn to immunoglobulins must be taken into account. There have been many studies on the composition of immune complexes isolated by various methods from human sera and other body fluids of individuals with a variety of diseases and from experimentally produced immune complex disease.
