Effect of a rice-rich diet on the therapeutic efficacy of cyclophosphamide with special reference to the enhancement of transplantation immunity.

The present study investigated the problem of whether the therapeutic efficacy of cyclophosphamide in the in vivo Ehrlich ascites tumor system can be improved by adjuvant use of hydrocortisone or of dietary hydrocortisone mobilizers. In the chemotherapy experiment, female ICR mice each received an inoculum of 1 x 10(6) cells of Ehrlich ascites tumor ip followed by 2 ip injections of cyclophosphamide 36 and 37 hr later (2.4 mg/mouse for the 1st injection, and 1.0 mg/mouse for the 2nd injection). The effects of both cyclophosphamide and adjuvant treatments were assessed in terms of either survival rate or cure rate in the 1-month experiment. The results obtained were as follows. 1) Prolonged use of hydrocortisone as an adjuvant can improve the survival of cyclophosphamide-treated mice. 2) Adjuvant use of a rice-rich diet for maintenance increased the rates of both survival and cure in the cyclophosphamide-treated mice. 3) The same maintenance of mice on a rice-rich diet increased transplantation immunity on the one hand, and induced a set of steroidal changes including hydrocortisone excess on the other hand. 4) Evidence is presented to indicate that the beneficial influence of a rice-rich diet on the drug effect is related to an increase of transplantation immunity in the host, and that there could be a causal relationship between hormonal and immunological changes in rice-saturated mice.