Objectives Until now the stimulating effects of these interferonogens have been shown for type I and II IFNs, however the data regarding induction of type III IFNs has not been available. Methods

The IFN (α, β, γ and λ2/3) inducing activities of low-molecular synthetic interferonogens tilorone (amixin), meglumine acridonacetate (cycloferon), sodium carboxymethylcellulose and gossypol conjugate (kagocel) are compared in CBA mice. Results

Administration of tilorone in comparison to cycloferon and kagocel has a significant dose-dependent effect on IFNs concentration in mice serum. Maximal level of all IFNs in serum was observed after 24 h of administration of tilorone (IFNα 176 ± 10 and 398 ± 12 pg/ml for the doses of 40 and 400 mg/kg, IFNβ 8 ± 4–110 ± 6, IFNγ 4 ± 1–46 ± 10, IFNλ2/3 1337 ± 93 and 2231 ± 93 pg/ml). Cycloferon and kagocel do not induce the increase of IFNα, IFNβ and IFNγ in mice serum. The highest level of IFNλ2/3 after introduction of kagocel at the both doses was seen after 48 h (616 ± 135–382 ± 46 pg/ml). Administration of cycloferon at a dose of 150 mg/kg significantly stimulated IFNλ2/3 level in serum after 72–120 h of administration (391 ± 31–388 ± 80 pg/ml). Cycloferon at the highest dose significantly increased the IFNλ2/3 levels between 12–24 h after administration (434 ± 79–441 ± 47 pg/ml).

Conclusion Tilorone induces synthesis of type I and type II IFNs as well as type III IFNs (IFNλ2/3) in serum, while administration of kagocel and cycloferon stimulates only type III IFNs (IFNλ2/3) in serum. Tilorone (amixin) has the widest spectrum of activity and is the most promising of the studied interferon inducers.