Intranasal peptide-induced tolerance and linked suppression: consequences of complement deficiency.

A role for complement, particularly the classical pathway, in the regulation of immune responses is well documented. Deficiencies in C1q or C4 predispose to autoimmunity, while deficiency in C3 affects the suppression of contact sensitization and generation of oral tolerance. Complement components including C3 have been shown to be required for both B-cell and T-cell priming.