マウス胸腺における抗体遺伝子の転写

Abstract

T and B cell developmental and functional status were investigated in the fetal and newborn mice. Interleukin (IL2) produced by activated T cells and immunoglobulin (Ig) heavy chain transcriptions were examined in thymus and spleen by RTPCR. In the 18 day embryo, T cells located in both organs because T cell receptor (3 chain (TCR (3) was transcribed. IL2 mRNA, however, was detected in the thymus, but little, if any, in the spleen of the embryonic stage. IL2 transcription was clearly observed in the spleen after birth. IgM heavy chain was transcribed both in the thymus and in the spleen of the embryo, and IgG3 and IgA were also done a little in the embryonic thymus. Because in aged thymus IgM, IgG3, IgA and IgE tran-scriptions could be clearly detected, the class-switching of heavy chain gene occurred in the thymus. Supernatant of primary cultured embryonic thymus cells for 48 hrs contained IgG3 and x chain of light chain. We conclude that lymphocytes in the embryonic thymus are already activated and able to interact with B cells of which Ig genes recombine the V domain for IgM, and that the class-switching of Ig heavy chain genes happen in the thymus. It should be clarified what antigens stimulate the thymus-cells to produce immunoglobulins, especially in embryo.