How to assess tumor-specific immune responses? Need to identify tumor-specific antigens, no mean feat since most of what a tumor expresses is similar to what normal cells express, at least as in so far as immunologically relevant material,, is concerned. Genetically engineering the mouse thymoma cell line EL4 to express the (OVA) protein, i.e., EL4-OVA, created a research tool to do just that.
Since the 1990s, T cell transgenic mice () have become basic immunology research models du jour. Among the most popular models in particular are T cell transgenics on the RAG ( ) knock out (KO) background. Knocking out the RAG-1 and -2 genes puts an end to the capacity for generating T and B cells. Thus a T cell transgenic mouse on the RAG KO background contains a monoclonal population of T cells expressing a single TCR ( ).
One of the most popular antigenic specificities chosen for creating such T cell transgenic mice has been OVA. For example the T cell transgenic mice OT-1 and OT-II on thebackground have a monoclonal population of CD8 and CD4 T cells, respectively, specific for OVA peptides. OTOH, the DO11.10 is an OVA peptide-specific CD4 T cell transgenic mouse on the background. C57Bl/6 and BALB/c are standard inbred mouse strains.
The EL4 mouse thymoma cell line was derived from a C57Bl/6 mouse. Making it express OVA made it a useful tool to assess anti-cancer immune responses in an antigen-specific manner. Typically, OT I and/or OT II T cells are injected into EL4-OVA tumor-bearing C57Bl/6 or C57Bl/6 RAG KO or WT (wild type) mice in various permutations and combinations. This makes it possible to use anti-OVA T cell responses as a surrogate for assessing anti-tumor T cell responses.