A cytotoxic substance (CTS-51) produced by human buffy coat cultures stimulated by staphylococcal enterotoxin B: further characterizations and combined action with interferon.

Abstract

A recently recognized unique cytotoxic substance, CTS-51, was tested for the hear or acid stability, trypsin digestion and dialysis. Moreover, influences of elevated incubation temperatures or serum concentrations of medium on the cytotoxic activity of CTS-51, and the combination effects of CTS-51 and human leucocyte interferon (HuIFN-alpha (Le)) were investigated. The cytotoxic activity of CTS-51, which is promoted by a small molecule easily passable the dialysis membrane, was found to be very stable to heat (even at 100 degrees C for 30 min) or acid (pH 2.0 for 24 hr at 4 degrees C) treatments. The treatment with 0.75% trypsin for 1 hr did not diminish the CTS-51 activity. The susceptibility of Daudi lymphoma cells to the antiproliferative action of HuIFN-alpha (Le) was further potentiated by treating the cells with CTS-51 for 16 hr. On the other hand, the CTS-51 activity which was revealed to be prescribed by its concentration in the medium, was not potentiated at 39 degrees C when compared to that at 37 degrees C in contrast to HuIFN-alpha (Le) action, and was reduced according to the increase of the fetal calf serum concentration in the medium.