Treatment
did not cause any signs of toxicity. Behavior, animal growth,
and weight of organs were similar to animals injected with
vehicle, and no histological abnormalities were found in the
organs. In vitro cell culture studies revealed no direct cyto-
toxic effect of SC3 towards sarcoma cells, while cytotoxic activity was observed towards melanoma cells at a high SC3
concentration. Daily treatment with SC3 did not result in
detectable levels of anti-SC3 antibodies in the plasma.
Instead, a cellular immune response was observed.
Incubation of spleen cells with SC3 resulted in a 1.5- to
2.5-fold increase in interleukin-10 and TNF-α mRNA lev-
els. In conclusion, the nontoxic fungal hydrophobin SC3
showed tumor-suppressive activity possibly via immunomo-
dulation and may be of benefit as adjuvant in combination
with chemotherapy and radiation.