Destruction of syngeneic tumors by tuberculin-stimulated peritoneal exudate cells from guinea pigs immunized to mycobacterium bovis (Strain BCG)

Peritoneal exudate (PE) cells from BCG-immune strain-2 guinea pigs were cytotoxic for syngeneic hepatoma cells when incubated in the presence of purified protein derivative of tuberculin. Significant tumor cell destruction occurred with as few as 4×10⁵ PE cells incubated with 4×10⁴ target cells. PE cells were separated into a nonadherent or lymphocyte-rich fraction and an adherent or macrophage fraction. The cytotoxicity of the nonadherent fraction was approximately equal to that of the unseparated PE cells from which the fraction was derived. Since the nonadherent subpopulation contained not only lymphocytes but also significant numbers of macrophages, cytotoxicity could have been due to lymphocytes and/or lymphocyte activation of macrophages. No cytotoxic role could be assigned to the adherent macrophage population.