Regeneration and the immune system. II. Suppressor activities of lymphocytes activated in vivo by liver regeneration and their genetic control.

The lymph node cells (LNC) activated in vivo by liver regeneration following partial hepatectomy of mice (primed lymph node cells) respond to regenerating liver cells in vitro with typical secondary immune response characteristics (Miyahara, S. et al., Eur. J. Immunol. 1983. 13: 878). These LNC activated in vivo suppress the proliferation of responder lymphocytes cultured with mitomycin C-treated regenerating syngeneic liver cells (sMLHLR). The suppressive activity was already present in LNC 4 days after partial hepatectomy and remained unchanged for at least 16 days. These primed LNC were effective not only on sMLHLR but also on syngeneic mixed lymphocyte culture (sMLR) and allogeneic mixed lymphocyte culture, of which responder cells share the I-A (I-B) subregions of the major histocompatibility complex (MHC) with primed LNC. At least one cell in the suppressor circuit is a T cell. The primed LNC restimulates in vitro with regenerating liver cells (in vitro reactivated primed LNC) suppressed the proliferation of syngeneic responder cells in sMLR, but not of cells from congeneic mice differing from the in vitro reactivated primed LNC at a cluster of genes linked to the Ig locus. Thus the suppressive activity of primed LNC is controlled by the I-A (I-B) subregions of the MHC and that of in vitro reactivated primed LNC by genes in the Ig region. The role of these suppressive cells in liver regeneration is discussed.