Mouse fetal liver cells manifest antigen-specific suppressor activity

Liver cells obtained from C57B1/6J mice at different stages of development suppress the primary in vitro induced immune response. Fetal liver cells showed the strongest suppression of the PFC response, an effect which was gradually lost after birth. Thymic or splenic cells were ineffective in suppressing the PFC response under conditions where fetal liver cells from the same donors were highly active. Liver cells from newborn C57B1/6J athymic nude mice were equally suppressive as cells from their normal thymus-bearing littermates. Preculture of liver cells from 18-day-old fetuses with antigen homologous to that used in the indicator system increased suppressor activity severalfold compared with other experimental groups in which cells have been precultured in medium alone or with the addition of a heterologous antigen. The data suggest that antigen-specific suppressor activity is present in fetal liver cells. The possible relevance of these findings in relation to acquisition of self-tolerance is discussed.