MOLECULAR CHARACTERIZATION OF COMPLEMENT COMPONENTS (C3, C4, AND FACTOR-B) IN HUMAN SALIVA

A molecular analysis of complement components (C3, C4, and factor B) i n human saliva was performed by SDS-PAGE and immunoblotting. Complemen t C3 was detected as a molecule composed of a 119-kDa alpha-chain link ed to a 70-kDa beta chain by disulfide bonds, and C3 levels ranged fro m 0.52 to 15.0 mu g/ml (n = 15). C4 was detected as a triple-chain mol ecule (98-kDa alpha chain, 73-kDa beta chain, and 33-kDa gamma chain) linked by disulfide bonds, and C4 levels ranged from 0.086 to 4.8 mu g /ml. Factor B was detected as a 100-kDa single chain, and factor B lev els ranged from 0.042 to 0.62/mu g/ml. The sizes and subunit structure s of the complement components in human saliva were compatible with th ose reported in human serum. The results of a hemolytic assay indicate d that the complement molecules in human saliva were functionally acti ve. These complement components may participate in the local immune an d inflammatory responses in the oral cavity.