Skin and heart allograft prolongation in tilorone-treated rats.

Tilorone is a synthetic amino-alkoxyfluorenone with demonstrated antiviral and antitumor properties. This study gives evidence for immunosuppressive properties of the substance as well. Buffalo rats (AgB6) received skin grafts from rats of the Fischer (AgB1) strain. Control animals rejected in 9.9 +/- 1.1 days, compared to 13.7 +/- 2.3 days for recipients treated with Tilorone. Steroids when combined with Tilorone further prolonged skin allografts to 16.7 +/- 2.6 days. Heart allografts from Fischer (AgB1) and Brown-Norway (AgB3) to Lewis (AgB1) also were performed. In the Fischer to Lewis combination, allograft survival was prolonged from 14.7 +/- 1.0 to 31.0 +/- 3.8 days. In the Brown-Norway to Lewis combination, treated rats rejected in 10.2 +/- 1.4 days versus 6.6 +/- 1.1 days for controls. Increased levels of cytotoxic antibody specific to lymphocytes of the donor strain were noted in Tilorone-treated animals. The mechanism by which Tilorone prolongs allografts may well involve a combination of interferon production and specific suppression of thymus-derived lymphocytes.

Prolongation of allografts in animals with a new agent: tilorone.

Tilorone, a synthetic amino-alkoxyflorenone, has been demonstrated to prolong allografts in rats and dogs. Tilorone, in combination with low dose non-specific immunosuppression, appears to have an additive effect. Tilorone's mechanism of action is unclear at this time but may involve a combination of specific T lymphocyte depletion and interferon induction.