Different courses of granulomatous reactions around Schistosoma japonicum eggs in three strains of mice.

Tissue reaction around Schistosoma japonicum eggs was studied after implantation into 3 strains of mice. When freshly laid eggs were implanted into the livers of C57BL/6, CBA/J, and BALB/c mice, the tissue reaction, which could be divided into 3 stages, i.e., abscess formation, inflammatory stage, and fibrous stage, differed in persistence and reactivity according to the strain. This was true especially during the later 2 stages. In BALB/c mice, the inflammatory stage ended earlier. In CBA/J mice, it continued for the longest period and the subsequent fibrosis was the most marked. In C57BL/6 mice, the period of persistence of this inflammatory stage was intermediate, but these mice showed the highest degree of inflammatory reaction. When footpad reactions were tested, the delayed-type hypersensitivity reaction was generally comparable with the morphometric analysis. In presensitized mice implanted with lyophilized eggs, tissue reactivity was analogous to the fibrous stage of freshly laid egg-implanted mice. In addition, there was an inverse relationship between antibody level and granuloma size, particularly at later reactions. The analysis of experimental granuloma formation presented in this report contributes to the study of stage-specific regulation.