RM-11, a new izoxasole derivative, is a potent stimulator of the humoral and cellular immune responses in mice.

In this report we describe immunostimulatory properties of RM-11 in several in vivo and in vitro tests in the murine model. We found that RM-11 significantly stimulated the humoral immune response to sheep erythrocytes (SRBC) when given intraperitoneally (i.p.) at doses of 10 and 100 microg or per os (doses of 20 and 200 microg) 3 h before immunization. The compound was also stimulatory with regard to generation of delayed type hypersensitivity (DTH) to SRBC when given i.p. or per os (doses of 10, 100 and 500 microg/mouse). The described immunostimulatory activities of RM-11 were higher compared to that of the reference drug, levamisole. RM-11 stimulated, in addition, concanavalin A (ConA)-induced splenocyte proliferation. Lastly, we showed that RM-11 was not toxic when given to mice per os at doses 250 mg/kg body weight. Taken together, RM-11 appeared to be a universal stimulator of the immune response in mice. Lack of toxicity and the ability to stimulate the immune response, when administered per os, predispose the compound for further preclinical studies.