Prolonged survival of tumor allografts in mice pretreated with soluble transplantation antigens

Immunogenic properties of rat hepatoma subcellular fractions

Subcellular fractions from an aminoazo dye induced rat hepatoma (D23) were examined for their ability to evoke rejection responses in syngeneic hosts to transplanted tumour cells and to induce the production of humoral antibody. Membrane fractions isolated by zonal centrifugation and displaying an increased activity of tumour specific antigen (Price and Baldwin, 1974), as well as crude membrane fractions and purified tumour cell ghosts, all elicited tumour specific antibody demonstrable by membrane immunofluorescence staining of viable hepatoma D23 cells. Tumour cell nuclei or soluble cytoplasmic protein were, however, lacking in this capacity. Resistance to tumour cell challenge was not observed in rats treated with any of the hepatoma D23 subcellular fractions administered by various routes either alone or in admixture with bacterial adjuvants. These findings are relevant to current views that tumour immunity may be more optimally achieved by inoculation of intact (viable or attenuated) tumour cells.

Induction of partial immunologic tolerance in rats and progressive loss of cellular antigenicity in Gross virus lymphoma

Gross virus-induced lymphoma cells express strong virus-associated (Gross murine leukemia virus [G-MuLV]) antigens and are consistently rejected when grafted in normal adult syngeneic rats. By contrast, similar grafts are tolerated and allowed to grow progressively by rats that have been injected at birth with deaggregated G-MuLV antigens. However, the tolerance induced by this procedure is only partial as the grafted lymphoma cells lose their G-MuLV membrane antigens. These cells showing an antigenic disjunction, with negative membrane and positive cytoplasmic G-MuLV antigenic expression, become transplantable in normal-nonconditioned adult recipients. By further grafting, the expression of cytoplasmic G-MuLV antigens is similarly lost while the lymphoma cells substantially increase their transplantability, rate of growth, and capacity for metastasis.