Potentiation of delayed-type hypersensitivity response to syngeneic tumors in mice prevaccinated with cells modified by hydrostatic pressure and crosslinking.

Delayed-type hypersensitivity (DTH) to the chemically induced EL4 and virally induced ARadLV 136 leukemia cells was determined by the radioactive ear test. Prior to the DTH test, mice were prevaccinated with cells treated either with hydrostatic pressure or with the membrane-impermeant crosslinker adenosine dialdehyde or with a combination of these. For both tumor cells, DTH against unmodified cells was markedly potentiated by prevaccination with cells treated with hydrostatic pressure combined with adenosine dialdehyde. In vitro cytotoxicity data indicated that maximal lysis of target cells is induced by vaccination with adenosine-dialdehyde-treated cells, as well as by pressure in combination with adenosine dialdehyde treatment. In addition, increased [3H]thymidine uptake was observed in effector T cells induced by prevaccination with tumor cells modified by adenosine dialdehyde or pressure or both. This novel and innocuous potentiation of an antitumor immune response may have a practical utility in the treatment of human cancer.