The immunocytochemical demonstration ofToxoplasma antigen in the brains of congenitally infected mice

Abstract

The peroxidase anti-peroxidase immunocytochemical staining method was used to identifyToxoplasma antigen in paraffin embedded sections of the brains of 22 mice congenitally infected with the parasite. IntactToxoplasma tissue cysts were readily demonstrated in the brain in all cases. In 4 of the 22 infected mice there was evidence of rupture of the cyst wall and/or presence of extra-cysticToxoplasma antigen. Further support for the extra-cystic location ofToxoplasma antigen was obtained by electron microscopy of reprocessed tissue which revealed endozoites in the area immediately surrounding a ruptured cyst. The possible implications of these findings in relation to the pathogenesis of congenital toxoplasmic meningo-encephalitis are discussed.