Cellular and humoral suppressor activity induced by concanavalin A-stimulated human fetal liver cells

Incubation of human fetal liver cells (HFLC), obtained from 8-12-week-old fetuses, with mitogenic doses of Concanavalin A (Con A) resulted in generation of a population that could suppress alloantigen-induced lymphoproliferation. The supernatant media in which these cells were activated suppressed DNA synthesis, both in mitogen and alloantigen induced peripheral blood lymphocyte cultures. Suppression was achieved only when the Con A-activated cells or the supernatants were added during the early stages of sensitization. Treatment of the cells with mitomycin C after Con A activation did not alter their ability to mediate suppression. This study indicates the presence of suppressor or presuppressor cells in the liver in the early period of fetal life. If the suppressor activity of HFLC in vitro is also induceable in vivo, it may contribute to the fetal defense mechanism against maternal rejection.