Correlation of T cell receptor gene rearrangements to T cell surface antigen expression and to serum immunoglobulin level in scid mice.

The severe combined immunodeficient (scid) mouse which has undetectable serum immunoglobulin (Ig) contains a small number of thymic lymphocytes which express Thy-1 and IL2 receptors (IL2R) but not Lyt-2 or L3T4 molecules. These thymocytes did not show any rearrangement of T cell receptor (TCR) beta-chain genes. Such thymocyte characteristics in the scid mouse were similar to the 15-day embryonic thymocytes in ordinary mice, indicating that the scid mouse thymocytes are arrested in the early stage of intrathymic differentiation. However, low or medium level serum Ig was occasionally found in the littermates of the scid mouse. The thymocytes of these mice showed some evidence of TCR beta-chain gene rearrangement and the presence of Lyt-2+/L3T4+ cells in correlation with the serum Ig level. In the mice with some serum Ig the thymocyte cell number was increased and the proportion of IL2R+ cells was decreased. Collectively, these results suggest that the rearrangement of TCR beta-chain genes is associated with the expression of Lyt-2 and L3T4 molecules in intrathymic differentiation and probably with cell proliferation of the migrated lymphoid cells in the scid mouse.