Fusion of B Lymphoblastoid and Tumor Cells Expressing Different Antibiotic Resistance Genes Facilitates Selection of Stable Hybridomas

Abstract

The development of tumor vaccines or generation of tumor-specific cytotoxic T lymphocytes (CTL) is limited by the fact that many tumor cells downregulate the expression of major histocompatibility complex (MHC) Class I and II molecules, as well as key co-stimulatory molecules such as CD80 and CD86. An immune response to a vaccine or in vitro stimulation of tumor-specific CTL requires antigen-presenting cells conveying tumor antigens in the context of a host's MHC antigens. We have used a retroviral vector (murine stem cell virus) encoding neomycin resistance to transduce three pediatric tumor cell lines (two neuroblastoma, one neuroepithelial tumor). An EBV transformed B lymphoblastoid cell line (BLCL) was transduced with a separate vector encoding puromycin resistance and green fluorescent protein, individual tumor lines were fused with the BLCL, and the resulting hybridomas were selected using both antibiotics. The resulting hybridoma cells expressed the neural antigen GD2 as well as MHC Class I, Class II, CD 80, and CD86. A similar strategy could be used to produce stable hybridomas for either vaccination or for CTL expansion.