The human gamma/delta + and alpha/beta + T cells: a branched pathway of differentiation.
In human peripheral blood, most of the CD3+ cells express the alpha/beta T cell receptor. A smaller fraction of CD3+ T cells express the gamma/delta T cell receptor (from 1 to 10% depending the individuals, with an average of 3-5%). Interestingly, although the alpha/beta + T cells never express the gamma chain at the cell surface, most of them (about 98%) rearrange the gamma locus on both alleles, the remaining 2% alpha/beta + T cells have one rearranged TRG locus. We previously proposed that V-J joinings in the human TRG locus occurred sequentially and we recently demonstrated that two successive rearrangements may occur on the same chromosome [Alexandre et al. (Int. Immunol, 3, 973-982, 1991)]. In this paper, we discuss the implications of these sequential rearrangements on the relatedness of the human gamma/delta + and alpha/beta + T cell lineages.
Alexandre
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Laboratoire d'Immunogénétique Moléculaire, LIGM, URA CNRS 1191, Université Montpellier II, France.
Lefranc
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D002454:Cell Differentiation; D015329:Gene Rearrangement, T-Lymphocyte; D006801:Humans; D008957:Models, Genetic; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta
D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta