The interferonogenic agent tilorone as a modulator of GvH reaction in mice.

The effects of tilorone hydrochloride (TH), a powerful interferongenic agent exhibiting also immune modulatory properties on GvH reaction was studied, using the popliteal lymph node assay in mice. Administration of TH at 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 days-4 or-2 induced an enhanced GvH reactivity 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, the latter of which are responsible for induction of 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.