The transgene contains the human CD8 alpha and beta chain genes driven by the T cell-specific Lck promoter. CD8alpha-alpha homodimers were expressed on 62% of thymocytes and CD8alpha-beta heterodimers on 14% of thymocytes. Peripheral T cells preferentially expressed the CD8alpha-beta heterodimers at a 4:1 ratio. Human CD8alpha was detected on both CD4+ and CD8+ T cells. (J:92994)