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One of the approaches to make anti-CD20 antibody more efficient is to express this antibody on the surface of T cells. scFv from anti-CD20 antibody has been expressed on T cell surface to bind to CD20 positive cells and CD3zeta has been expressed as a fusion partner to transduct signals. T cells grafted with this chimeric scFv/CD3zeta were able to redirect grafted T cells to an MHC/Ag-independent antitumor response. To test the effects of CD28 signal on the cellular activation and antitumor effectiveness of chimeric scFv/CD3zeta modified T cells, we constructed a recombinant anti-CD20 scFv/CD28/CD3zeta gene in a retroviral vector. T cells expressing anti-CD20 scFv/CD28/CD3zeta specifically lysed CD20 positive target tumor cells and secreted not only IFN-gamma but also IL-2 after binding to their target cells. Our data indicate that CD3 and CD28 signalling can be delivered in one molecule, which is sufficient for complete T cell activation without exogenous B7/CD28 costimulation.

The antitumor effect of PSK was analysed with the "double grafted tumor system" in which BALB/c mice received simultaneous intradermal inoculations of Meth-A in the right (10(6) cells) and left (2 x 10(5) cells) flanks and were then injected with PSK in the right tumor on day 3. PSK inhibited the growth of not only the right but also the left, non-treated tumor. Immunized spleen cells were taken from mice which had been cured by intratumoral administration of 5 mg of PSK. On day 3, one hour after intravenous injection of cyclophosphamide, immunized spleen cells (2 x 10(7) cells/mouse) were injected into the Meth-A tumor. Adoptive transfer of PSK immunized spleen cells caused the complete regression of Meth-A tumors. However, the intravenous administration of spleen cells showed no antitumor effect. Expansion of peripheral blood lymphocytes was stimulated with immobilized anti CD3 antibody plus IL-2 for use in adoptive immunotherapy. gamma delta T cells proliferated in response to immobilized anti CD3. About 5 x 10(9) BRM-activated killer (BAK) cells were treated in cancer patients who gave their informed consent. One patient with colon cancer and metastatic cancer of the liver was treated with BAK cells by transcatheter arterial infusion without side effect. During the course of BAK treatment, serum IAP CIAE (crossed immunoaffino electrophoresis) pattern of patient changed tumor IAP pattern to normal IAP pattern. Two patients with malignant tumor in maxillary sinus were treated with BAK cells and OK-432 intratumorally. BAK treatment induced more infiltration of T cells, M phi and granulocytes in the tumor than OK-432 treatment alone and showed an antitumor effect with extensive necrosis.

Peripheral blood lymphocytes separated from about 20ml of blood were cultured with immobilized anti-CD3 antibody and IL-2. Total T lymphocytes in the culture expanded about 2,000 times by 2 weeks culture. Expanded T lymphocytes were infused to cancer patients, and safety and feasibility was confirmed. This method will be applicable for prevention of cancer recurrence.