UBC Theses and Dissertations
Enhancement of an anti-tumor immune response using bacteriophage T4 as a linked helper determinant on P815 tumor cells Bridgett, Margot M.
Heterogenization is defined as the enhancement of weak anti-tumor responses by attachment of strong antigenic helper determinants to the surface of tumor cells. Anti-tumor immune responses may be further amplified by addition of T helper cells specific for the helper determinant. I investigated the effectiveness of bacteriophage T4 (0T4) as a helper determinant in the heterogenization of P815 tumor cells. Experiments were performed to quantitate and optimize chemical coupling of 0T4 to irradiated P815 tumor cells (P815r). Proliferation assays showed that T cells primed in vivo to 0T4 could recognize 0T4 that was chemically linked to P815r (P815r-0). T cells primed in vivo with P815r-0 responded in the proliferation assay to free 0T4. An in vivo adoptive transfer system W8S used to examine the helper ability of 0T4-primed spleen cells. 0T4-primed, irradiated spleen cells and SRBC-primed B cells were transferred into irradiated host mice. The anti-SRBC response of the transferred SRBC was augmented only when the mice were challenged with SRBC linked to 0T4. Challenge with SRBC and free 0T4 did not increase the response. A 0T4- specific T helper cell line was established and maintained in vitro. The cell line was cloned by limiting dilution and the clones were characterized as to their proliferative response to 0T4 and their production of interleukin 2. When added to cultures of spleen cells that were stimulated with either P815r-0 or P815r and free 0T4, the cell line dramatically enhanced the killing of P815 tumor cell targets by cytotoxic T cells. Elimination of in vitro primed T helper cells using antibody plus complement was essential to detect this result. The T helper cell line and clones were tested in in vivo immunotherapy trials. Mice were treated with cyclophosphamide to reduce suppression in the animals, injected with T helper cells and immunizing doses of P815r-0, and challenged with viable P815 tumor cells. The cells line and clones demonstrated in vivo helper activity. Optimal conditions for performance of the immunotherapy experiments are discussed.