Selection of Human TcR V Gene Families in Autologous Mixed Lymphocyte Reactions: Relevance to Autoimmune Immunopathology

Abstract

We have postulated that in vivo autologous mixed lymphocyte reactions (AMLRs) are one mechanism in the development of the intrathyroidal lymphocytic infiltration of human autoimmune thyroid disease. Such a mechanism would explain the significant numbers of self-reactive T cells present in thyroid infiltrates as evidenced by cloning studies. However, infiltrating T cells in a variety of autoimmune diseases including autoimmune thyroid disease, demonstrate bias in their use of T cell receptor (TcR) V gene families. In order to examine whether such TcR V gene bias may occur secondary to non-antigen specific in vivo AMLRs rather than secondary to specific autoantigen driven mechanisms we have examined the human TcR repertoire after prolonged AMLRs in vitro. Using 5 healthy donors in 1, 2 and 3 week AMLRs we showed stimulation indices of 3.1–6.5 after 3 weeks. The hTcR Vα and Vβ gene repertoire was assessed using the PCR technique and revealed an almost complete repertoire of V gene families at the beginning of the studies while at the end of 3 weeks a mean of only 5.2 Vα genes were transcribed. Less restriction was seen in the hTcR Vβ repertoire with a mean of 9 Vβ genes used. These data demonstrate that the AMLR is able to mimic the marked bias in hTcR V gene family use seen within the inflamamatory infiltrates of autoimmune diseases.

Key Words:

• TcR gene families
• MLR autoimmune reaction