title: C4 nephritic factor in a patient with chronic glomerulonephritis.
abstract: C4 nephritic factor (C4NeF) was found in the serum of a patient with chronic glomerulonephritis, whose C3 level was quite low (less than 1% of normal). C4NeF prevented the intrinsic decay of C4b2a enzyme and prolonged the half life of the C4b2a from several minutes to more than 1 h in the solid and fluid phase. The C4NeF activity was associated with a protein fraction immunochemically identified as the IgG3 subclass and it bound specifically to the EAC142 cells. In addition, the patient's serum contained C3-cleaving activity, probably C4b2a, C4NeF complex, which may have lowered the level of C3 in the patient's serum. Spontaneously, the titer of C4NeF decreased, while the level of C3 increased.
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: T
authors.initials: T
authors.lastname: Sumita
authors.forename: S
authors.initials: S
authors.lastname: Yoshida
authors.forename: S
authors.initials: S
authors.lastname: Ito
authors.forename: N
authors.initials: N
authors.lastname: Tamura
mesh_terms: D002908:Chronic Disease; D003176:Complement C3 / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005921:Glomerulonephritis / Q000276:immunology*; D006462:Hemolytic Plaque Technique; D006801:Humans; D007120:Immunochemistry; D008875:Middle Aged
chemical_list: D003176:Complement C3; D003181:Complement C4