Note: On a few occasions NIAID has detected the suppression of or the loss of DO11.10 in lines containing this transgene. They are investigating this further and increasing the frequency of their quality control for these mice. However, it would be advisable to re-test the lines upon receipt. Any mice found not expressing the transgene will be replaced at no cost to the investigator. The preferred method of testing is flow cytometry of blood using the clonotypic monoclonal antibody KJ1-26 from Pharmingen. The Transgenic DO11.10 T Cell Receptor mouse was generated by Dr. Ken Murphy in the Laboratory of Dr. Dennis Loh at Washington University, St Louis in 1989. The line was made with the rearranged Vβ 8.1 and Vα 13 T cell receptor genes of the Kappler and Marrack OVA-specific T cell hybridoma DO11.10 using (C57BL/6 x C3H/HeJ)F1 x BALB/c donor embryos. The founder line has two copies of the Vα gene and four copies of the Vβ gene cointegrated onto the distal part of chromosome 18. It was initially backcrossed to BALB/c 6 times. The line was then transferred to Dr. B.J. Fowlkes at NIH and backcrossed to B10.D2/AiTac, selecting for idiotype+ offspring by flow cytometry typing of peripheral blood with the KJ1-26 monoclonal antibody. At N3 it was embryo transfer-derived into the NIAID Repository at Taconic via one further backcross mating to B10.D2/AiTac. The mice were crossed four more times to B10.D2/AiTac. The N8 offspring were then crossed twice to a homozygous Rag2 knockout mouse on a B10.D2/Ai (N11) background and Rag2-/-, transgene positive offspring selected. These mice were then intracrossed to produce the line homozygous for the TCR transgenes. TCR homozygotes were selected by test mating the mice to wild type partners and identifying the animals that only gave rise to transgene positive offspring.