Deficiencies of C4A or C4B in Human SLE

Low Complement Activity and C4 Protein Concentrations in SLE It has been known for over half a century that SLE patients manifest reduced complement hemolytic activity (CH50) (Vaughan et al., 1951 Elliot and Mathieson, 1953). Reduced serum or plasma levels of complement C1q, C4, and C3 have been consistently observed in lupus patients, particularly those with lupus nephritis (Lewis et al., 1971 Cameron et al., 1976 Hebert et al., 1991). Serial analysis of serologic factors in SLE revealed...