EXPRESSION OF THE ALPHA-BETA-T-CELL RECEPTOR IS NECESSARY FOR THE GENERATION OF THE THYMIC MEDULLA

The architecture of the thymus of mice that congenitally fail to expre ss the alphabeta T-cell receptor (TCRalphabeta) has been examined by i mmunohistology. In these mice, a defined mutation was introduced into the TCRalpha gene by homologous recombination. By using antibodies spe cific for cortical or medullary epithelium and for major histocompatib ility complex antigens, the network of cortical epithelium in these mi ce was shown to be essentially unaltered in comparison with that of no rmal mice. In contrast, the thymic medulla was considerably reduced in size. This analysis shows that expression of the alphabeta TCR but no t the gammadelta TCR is obligatory for establishing the thymic medulla and suggests that the growth of medullary epithelial cells may requir e contact with TCRalphabeta-expressing cells.