Adoptive immunotherapy of human cancer has had limited success, but involves cumbersome and prolong cell culture. Pharmacologic activation of T cells from tumor-bearing hosts (TBH) with the PKC activator bryostatin 1 (Bryo) + ionomycin (Io) and culture in low-dose interleukin-2 (IL-2) induces rapid expansion of lymphocytes with therapeutic activity. This method will now be extended to nonimmunogenic tumors, using vaccination with tumor cells plus: 1) bacterial adjuvant or 2) recombinant interferon-gamma (IFN-gamma) or 3) non-malignant cells genetically engineered to express IL-2 or IFN-gamma. Since the objective is only to sensitize T cells for later """"""""amplification,"""""""" these vaccines need not be able to induce systemic immunity or tumor regression themselves. Whether cyclophosphamide pre- treatment will allow these sensitization strategies to succeed in the face of preexisting metastases will also be determined. The second major aim will be to apply the principles of in vitro pharmacologic T cell activation to develop novel and logically sequenced immunotherapeutic strategies that minimize or even eliminate the need for cell culture. The organotellurium compound AS101 will be tested as a replacement for Io to activate T cells in vitro. The anti-tumor effect of exposing T cells to Bryo + AS101 for very short periods in vitro and then reinfusing them into adoptive hosts with IL-2 will then be tested. Using response surface analysis, the optical combination of Bryo + AS101 for in vivo T cell activation will be determined. Then, these drug doses will be tested for """"""""amplification"""""""" of T cell sensitization to induce tumor immunity and regression. Bryo + Io- activated lymphocytes from breast cancer patients grow rapidly and secrete IFN-gamma and tumor necrosis factor-alpha in response to autologous tumor. The full spectrum of cytokine responses and the T cell subsets involved will now be determined. It is not known whether these T cells recognize small peptides associated with MHC or mucin core peptide epitopes in a non-MHC restricted manner. Using monoclonal antibodies and B cell lines genetically engineered to express the MUC1 epitope, this question will be answered. The hypothesis that IFN-gamma might increase the weak immunogenicity of breast cancer cells isolated from patient samples will be studied by examining its effects on: 1) expression of MHC antigens and ICAM-1, using FACS, and 2) any defects in the ability of breast cancer cells to process and present endogenous antigens with Class I. The latter will be examined using the susceptibility of target cells infected with a recombinant Vaccinia-K/d construct to lysis by murine vaccinia-specific CD8+ T cells. Taken together, these studies should lead to novel strategies for immunotherapy of human cancers, especially breast cancer, that are more effective and practical than any now available.
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