Effect of lentinan on tumor growth in murine allogeneic and syngeneic hosts.

The effect of lentinan on retardation and regression of transplanted tumors was analysed in allogeneic and syngeneic tumor-host systems. The effect of lentinan treatment was most variable in random-bred Swiss albino mice bearing sarcoma 180. With inbred host strains, it was most effective in A/PH and less, or not at all, in others (A.BY, A.CA, A.SW, DBA/2, BALB/c, C3H/Di, AKR, BIO, BIO.1, BIO.BR, BIO.D2). In order to eliminate the allogeneic differences, a syngeneic transplantable 3-methylcholanthrene-induced sarcoma (A/PhMC.SI) has been developed in the A/Ph strain, previously found to be the most responsive to lentinan. The growth of this sarcoma was dramatically inhibited and regression was detected in all lentinan-treated syngeneic recipients. Both the lentinan-treated and untreated regressor animals exhibited a high degree of resistance to a secondary challenge. However, the growth of a spontaneous, transplantable syngeneic adenocarcinoma in A/Ph mice was not influenced by lentinan treatment. The results presented substantiate further the conclusion that the effect of lentinan is mediated through host mechanisms, and show that these mechanisms are able to act against a syngeneic tumor.