[Effects of pretreatment with lentinan or krestin on antitumor effector cell activities suppressed by...

The author examined effects of BRMs such as Lentinan (LTN) and Krestin (PSK) on antitumor effector activities of spleen cells suppressed by cyclophosphamide (CY: 150 mg/kg, i.v.) in normal C57BL/6 mice in order to define the immunological significance of those BRMs when combined with CY treatment. When the mice were treated with CY alone, the total number of cells, and NK and LAK precursor cell activities per spleen were reduced to the nadir on day 3, and they eventually recovered, reaching normal levels on day 7. It was noted that the LAK precursor activity, but not NK cell activity, per 10(6) of spleen cells was significantly suppressed by CY. When LTN or PSK was administered for 7 days prior to the CY treatment, the reduction of total number and NK cell activity, but not of LAK precursor activity, was alleviated at the nadir on day 3. LTN- or PSK-administration also promoted the recovery of the total number, NK and LAK precursor cell activity on day 7. Interleukin-2 (IL-2)-production of concanavalin A-stimulated spleen cells was suppressed by CY, and recovered rather gradually without complete restoration even on day 9. LTN or PSK markedly prevented the CY-induced suppression and promoted the recovery of IL-2-production. These findings reveal that LTN or PSK exhibits lightening or restorative effects on CY-induced suppression of antitumor effector activities of murine spleen cells.