Intrathymic Differentiation and the T Cell Repertoire

Abstract

In the 1960’s immtinologists realised that the thymus was of critical importance in the development of the immune system. Without the thymus, T cell numbers were considerably reduced. In the 1970’s, immunologists went beyond this concept of a quantitative influence on peripheral T cell numbers, and there was a rush of enthusiasm for the idea that the thymus played an important role in determining the speci ficity of the cells produced.^1,2 The recent rapid advances in our understanding of the molecular nature of the T cell receptor and its associated molecules, may mean that the 80’s will give us a clearer picture of the mechanisms involved in this determination of the T cell repertoire. But while we await these revelations, it may be worth stepping back a little and taking a look at what our current knowledge of thymocyte subpopulations and kinetics tells us, and to see how the recent advances can best be applied.