Exclusion and Inclusion of α and β T Cell Receptor Alleles in Different T Cell Lineages

Abstract

The introduction of αβ T cell receptor genes into rearrangement deficient and normal mice has shown that T cell development is very tightly controlled by these genes (von Boehmer 1990, Scott et al. 1989, Teh et al. 1988, Kisielow et al. 1988). It is probably useful to distinguish an early developmental phase controlled by the β TCR chain only from a later phase controlled by the complete αβ TCR (von Boehmer 1990). The early phase of development has been less extensively discussed simply because the expression of the β TCR chain in the absence of the a TCR chain on developing T cells has escaped detection for many years. The later phase of development has been extensively reviewed and consists of positive and negative selection of lymphocytes according to the specificity of their receptor such that nonselected cells die, positively selected cells survive and negatively selected cells undergo rapid apoptosis (Huesmann et al. 1991, Swat et al. 1991). The delineation of the main developmental pathway of αβ T cells in αβ TCR transgenic mice has also resulted in the recognition of an unusual αβ lineage which is subject to different selection mechanisms (von Boehmer et al. 1991). In the following we will focus on the expression and allelic exclusion of a and β TCR genes in early development as well as in different αβ T cell lineages.

The Basel Institute for Immunology was founded and is supported by F. Hoffmann-La Roche Ltd., Basel, Switzerland