The mechanisms of increased host resistance to
tumors following treatment with
Z-100, an
arabinomannan extracted from Mycobacterium tuberculosis, were investigated in mice bearing syngeneic solid
tumors. When BALB/c mice bearing Meth-A solid
tumors were treated intralesionally (i.l.) with
a 10 mg/kg dose of
Z-100, 74% of
tumor growth was inhibited in the test group as compared with control mice treated with saline. However, no significant
tumor inhibitory activity was observed when these mice were treated with various doses of
Z-100 i.p. or i.v. In addition,
tumor growth in X-irradiated mice (450 R, whole-body irradiation) and in mice treated with
antilymphocyte serum was not suppressed even though
Z-100 was administered into the
tumor. The number of lymphocytes isolated from Z-100-treated
tumor tissues increased 3.2-fold (14 days after the
tumor inoculation), whereas no change in the number of tumor-infiltrating lymphocytes was demonstrated in mice treated with
Z-100 i.p. or i.v. as compared to controls. When BALB/c mice were inoculated s.c. with a mixture of Meth-A
tumor cells (1 x 10(6) cells) and lymphocytes (2 x 10(5) cells) derived from Z-100-treated
tumor tissues in a Winn's neutralization test, decreased growth of solid
tumors was demonstrated as compared with that of control mice inoculated with
tumor cells alone. However, no such inhibition of
tumor growth was observed in mice inoculated with a mixture of the
tumor cells and lymphocytes obtained from
tumor tissues of control mice at the same effector to target cell ratio.(ABSTRACT TRUNCATED AT 250 WORDS)