Induction of experimental murine granuloma formation against Schistosoma japonicum eggs produced by in vitro ova deposition, in vitro tissue extraction, or lyophilization

Abstract

Fresh eggs, laid by Schistosoma japonicum adult worms in vitro or recovered from tissue after trypsin digestion, as well as non-viable lyophilized eggs were injected into mice via the cecal vein. The freshly laid eggs induced a marked, maximal reaction at 2 weeks after implantation. This reaction was indistinguishable from that seen early in naturally infected mice. Lyophilized eggs induced granulomas only one-tenth the size of those formed around freshly laid eggs. Maximal granulomatous reactivity was not seen until the 4th week after implantation and the intensity of cellular reactivity and associated histopathological change was much lower than that observed with freshly laid eggs. Reactions against live, tissue-extracted eggs were quantitatively and temporally intermediate between those observed against laid and those surrounding lyophilized eggs. The results suggests that these differences in granuloma formation are due to variable quantities of locally produced cytotoxic materials and/or antigen that stimulate immune reactions of different intensities.