Issues of the study: Some kinds of mushrooms have been traditionally used as functional foods for the prevention or treatment of malignant diseases. Although the immunological mechanisms by injection of active components derived from edible mushrooms have been thoroughly examined, few studies are available on the mechanisms by oral administration. Therefore, we investigated the effects of oral administration of edible mushroom extracts on immune responses in gut-associated lymphoid tissue of mice in order to identify the active structure and the mechanisms.

Methods: B7/P815 tumor cells were transplanted into the subserosal space of the cecum in DBA/2 mice. High molecular weight fractions derived from hot water extracts of fruit bodies of edible mushrooms were orally administered daily 10 times, and the activity of mesenteric lymph node (MLN) cells was measured by the use of in vitro mixed tumor cells lymphocyte reaction (MLR) and MLR-cell-mediated cytotoxicity.

Results: 1) Among 12 samples examined, only the extract from Tricholoma matsutake significantly enhanced the responses. 2) When the extract from T. matsutake was fractionated, the activity

1.Department of Life Sciences, Kansei Fukushi Research Center, Tohoku Fukushi University, 6-149-1, Kunimigaoka, Aoba-ku, Miyagi 989-3201, Japan.

2. Biomedical Research Laboratories, Kureha Chemical Industry Company Limited, 3-26-2, Hyakunin-cho, Shinjukuku, Tokyo 169-8503, Japan. Correspondence to: Kenichi Matsunaga, Ph. D., Biomedical Research Laboratories, Kureha Chemical Industry Company Limited, 3-26-2, Hyakunin-cho, Shinjuku-ku, Tokyo 169-8503, Japan; Tel 813-3362-7326; Fax 81-3-3362-8523; E-mail address matsunaga@kureha.co.jp

was recovered in the em2 fraction which was prepared by treating the DEAE column-adsorbed fraction of the extract with B-1,3 glucanase. The effects of em2 were dependent on the timing of administration and the dose administered. 3) The physicochemical analysis revealed that em2 is a glycoprotein.

Conclusion: These findings suggest that a glycoprotein derived from fruit bodies of

T. matsutake enhances the activity of MLN cells by oral administration.