Enhanced recovery of NK cell activity in mice under restraint stress by the administration of a biological response modifier derived from the mycelia of the basidiomycete Tricholoma matsutake

Some types of stressor act on the immune system via the network comprising the endocrine-immune-nervous systems, and are reportedly responsible for the onset of diseases as well as giving impetus to their advance. It is important for the maintenance and promotion of health to cope with stress-induced changes in immunocompetence. Therefore, we studied the effects of administration of a novel biological response modifier (CM6271) derived from the mycelia of the basidiomycete Tricholoma matsutake on the NK cell activity in mice under restraint stress, in order to evaluate its potential to modulate immune responsiveness in stress-loaded individuals. (1) When C57BL/6 mice were restrained in 50-ml tubes for more than 6 h, splenic NK cell activity decreased significantly, but recovered gradually after the mice were released. The extent of the reduction of activity and the degree of recovery depended on the duration of the restraint. (2) The oral administration of CM6271 caused a significant acceleration of the recovery of the activity. This effect was dependent on the timing of administration and the dose given. (3) The administration of CM6271 had no clear effect on the blood levels of ACTH, corticosterone or lipid peroxide levels in the liver. These findings suggest that CM6271 promotes recovery from the decrease in NK cell activity induced by restraint stress.