FURTHER-STUDIES ON THE CIRCULATING M ANTIGEN IN HUMAN AND EXPERIMENTAL SCHISTOSOMA-MANSONI INFECTIONS

Abstract

Circulating M antigen [Ag], previously described in urine from patients infected by S. mansoni, was shown in serum from infected patients, using human anti-M immune serum with immunodiffusion and immunoelectrophoretic analyses. This Ag was present in the serum and urine from infected hamsters, in the urine from infected rabbits and in the serum from infected mice. It generally appeared on day 20 after infection. M Ag was specific for the genus Schistosoma and for the immature and adult worm stage. Its electrophoretic migration was cathodic. The MW of urinary M Ag was around 45,000 daltons. The M Ag was thermostable, soluble in trichloroacetic acid and contained no lipid component. It was not hydrolyzed by protease, RNase, amylase or neuraminidase, but was destroyed by sodium metaperiodate. All these properties betoken the polysaccharidic nature of M antigen.