Mitogenic activities of heteroglycan and heteroglycan-protein fractions from culture medium of Lentinus edodes mycelia.

The water soluble material (LEM) was prepared from the solid culture medium in which Lentinus edodes mycelia were growing actively. An alcohol insoluble material was prepared from LEM and subjected to Sepharose 6B gel filtration. The void fraction (LAP1) was composed mainly of xylose-rich heteroglycan and protein. From LAP1, a heteroglycan fraction (LAF1) was prepared by DEAE-Sepharose CL-6B column chromatography. LAP1 and LAF1 enhanced the incorporation of [3H]thymidine into mouse splenic cells (SPs). At each of the optimum doses, the rate of the incorporation was about 10 times as high with LAF1 as with LAP1. Such mitogenic responses were not induced in nylon-column effluent SPs and thymocytes. sIg-expressed cells were responsive to LAF1, but not to LAP1. Moreover, with each fraction, the incorporation was enhanced more in plastic adherent splenic cells (ADs) than in SPs. The flow cytometric assay revealed that the number of Mac-1+ cells is about 13 times as many in ADs as in SPs and that the number of Ly-5+ or Thy-1.2+ cells is considerably reduced in ADs compared with that in SPs. Thus, the present studies suggest that LAP1 and LAF1 act as mitogens predominantly for mouse splenic macrophages and/or monocytes.