Role of a streptococcal antigen in the pathogenesis of acute poststreptococcal glomerulonephritis. Characterization of the antigen and a proposed mechanism for the disease.
We studied the significance of a streptococcal protein (preabsorbing Ag) (PA-Ag) in the pathogenesis of acute poststreptococcal glomerulonephritis (APSGN). This protein was isolated from nephritogenic streptococci. Purification of PA-Ag was achieved by chromatography, followed by Sephadex IEF. A single protein band at pH 4.7 was identified as PA-Ag. The m.w. was 43,000. Rabbit antisera against PA-Ag and sera of patients with APSGN showed identical precipitation lines by immunodiffusion. Antibodies to PA-Ag were found to be present in 30 of 31 patients with APSGN, in 1 of 36 patients with uncomplicated group A streptococcal upper respiratory tract infections, and in 1 of 36 normal adults. By using immunoelectrophoresis, it was found that PA-Ag activates the alternate pathway of C. Other water-soluble streptococcal fractions, used as controls, did not activate the C system. The demonstration that PA-Ag is present in the glomeruli in the early phase of APSGN and its ability to activate C3 and factor B suggest that PA-Ag may be involved in the pathogenesis of APSGN, via in situ C activation.
Yoshizawa
N
N
Second Department of Medicine, National Defense Medical College, Tokorozawa, Japan.
Oshima
S
S
Sagel
I
I
Shimizu
J
J
Treser
G
G
D000208:Acute Disease; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000276:immunology* / Q000302:isolation & purification; D003167:Complement Activation; D005921:Glomerulonephritis / Q000209:etiology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008969:Molecular Sequence Data; D011817:Rabbits; D013290:Streptococcal Infections / Q000150:complications*; D013297:Streptococcus pyogenes / Q000276:immunology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007074:Immunoglobulin G