Effect of tilorone hydrochloride on graft-versus-host (GvH) reaction in mice.

The effects of tilorone hydrochloride (TH), a powerful interferonogenic agent exhibiting also immune modulatory properties, on GvH reaction was studied, using the popliteal lymph node assay in mice. Administration of TH at ten days 0 or +2 relative to cell transfer to recipient mice led to a significant dose-dependent reduction of GvH reaction, whereas treatment of prospective donor mice at day -4 or -2 induced an enhanced GvH re activity of donor spleen cells. This effect was found not to be due to an altered proportion in the spleen cell inoculum of B and T lymphocytes, which latter are responsible for induction for GvH reaction. However, since normal parental lymphocytes are prepared for an enhanced GvH reactivity by addition of TH-treated macrophages, a stimulatory effect of the latter cells via macrophage-derived mediators, induced by TH, is suggested.