Survival time of tumor-bearing rats as related to operative stress and immunopotentiators.

To investigate the mechanism of tumor growth enhancement induced by operative stress in rats, laparo-thoracotomy was performed on day 2 after tumor cell inoculation associated with administrations of various kinds of immunopotentiators. OK-432 (Streptococcal preparation), PS-K (extract from mycelium of Coriolus Versicolor), Lentinan (extract from Lentinus Edodus) and C. parvum were administered intravenously or intraperitoneally in the fractionated form prior to or after inoculation. In general, administration of each immunopotentiator, except for Lentinan, resulted in a recovery from the reduction in survival days after laparo-thoracotomy. In particular, OK-432 administration prior to inoculation showed a significant improvement.