1. Selection of non-toxic dose range of various G. lucidum extracts

   Using 10-fold dilutions of G.L., Bioherb and lentionan, it was found that concentrations of G.L. at 1:10, Bioherb at or above 10 mg/ml were lymphocytotoxic as seen by suppression of PHA-stimulated lymphocyte transformation whereas lentinan at a concentration as high as 250 μg/ml was not lymphocytotoxic (Table 1). In addition, the non-toxic dose of these G. lucidum extracts were non-mitogenic by themselves (data not shown).

2. Effect of G. lucidum extracts on the phenotype of T cell subsets after in vitro incubation

    Table 2 shows the change in CD4+ T cells after 3-day culture with various concentrations of Bioherb and lentinan. Approximately 1/3 to 2/3 of asymptomatic or PGL patients would have increase in CD4+ T cells after 3-day incubation with 10 mg./ml of Bioherb. The increase may be as high as 100% or more. The increase was less obvious with CD4 cells from normal individuals who had higher CD4 counts. The effect was also less with lentinan. In contrast to CD4 cells, CD8+ T cells almost had no changes after incubation with Bioherb or lentinan (data not shown).

3. Immunostimulatory effect of G. lucidum extracts on PHA-stimuulated lymphocyte proliferation

   The effects of various concentrations of different extracts of G. lucidum on PHA-stimulated lymphocyte transformation were tested with both the optimal (25μg of PHA/well) and the suboptimal doses (10/Ig/well) of PHA. Only a quarter to one half of the patients with asymptomatic HIV infection or PGL whose PHA-stimulated lymphocyte proliferation could be enhanced by cocultivation with G. lucidum extracts (Table 3). The crude hot-water extract of locally cultivated G. lucidum and Bioherb were more effective than lentinan. The immunostimulatory effect was more evident with suboptimal PHA stimulation than optimal PHA stimulation and with immunocompromised lymphocytes (i.e., Lymphocytes from patients with HIV infection) than lymphocytes from normal individuals. However, with severely immunocompromised lymphocytes such as those from ARC and AIDS patients, none of the G. lucidum extracts could show any immunostimulatory effects (data not shown).