lacks_plasma_membrane_part thymocyte double negative thymocyte double negative T cell 2010-12-06T03:03:38Z A thymocyte that lacks expression of CD4 and CD8. CD4-CD8- T cell These are precursors to mature T cells; normally, they do not circulate, but are found in the thymus and they have not undergone rearrangement of the alpha and beta T cell receptor genes. CD4 molecule T cell receptor co-receptor CD8