Comparative studies on immunological properties of antitumor polysaccharide TC-13

The biological and immunological characteristics of TC-13, an antitumor protein-bound polysaccharide, were studied. TC-13 had no direct cytocidal effect on Ehrlich carcinoma, but it induced antitumor resistance in mice whose tumors were regressed by TC-13. TC-13 changed the electrophoretic pattern of serum proteins of mice after its ip administration, causing a slow increase of the LB component and a rapid increase of the X component. TC-13 augmented the delayed-type hypersensitivity reaction to tumor homogenate, anti-SRBC antibody formation and the cytocidal activity of macrophages in an antibody-dependent system, but it had little or no effect on blast formation of spleen lymphocytes or carbon clearance. These results and comparative studies with other immunomodulators suggest that TC-13 is a unique polysaccharide having properties intermediate between those of lentinan, a simple-structured homologous polysaccharide from basidiomycetes, and lipopolysaccharide, a cell-surface component from bacteria.