ABSTRACT
Primary immune deficiencies of the complement system have been described for many of the complement components and their inhibitors, some in terms of specific gene mutations. Patients with a deficiency of certain of these complement components (especially C3) are prone to recurrent infections both with encapsulated organisms such as Pneumococcus and Streptococcus and with Neisseria (Table 1). The attachment of complement to the surface of some of these organisms is clearly important for their removal by phagocytic cells. Deficiencies in the later complement components and in the regulatory molecules of the complement system also result in increased susceptibility to infections by meningococci (e.g., Neisseria) or to inflammation, respectively.
