International Immunology, Vol 10, 951-960, Copyright © 1998 by Oxford University Press
H Kishi, JJ Tong, T Nagata and A Muraguchi
Previously, we described a mAb (1-23) reacting with a novel cell surface
antigen expressed on thymocytes at late CD4-CD8- [(double negative (DN)] to
early CD4+CD8+ [(double positive (DP)] differentiation stage. Since the
expression of this molecule was restricted to immature thymocytes, we
designated it as immature thymocyte antigen-1 (IMT-1). In this study, we
have investigated the relevance of IMT-1 expression to thymocyte selection
using TCR transgenic mice, scid mice or RAG-2-/- mice. The IMT-1+
population in DP thymocytes was decreased in the thymuses of MHC class
I-restricted or class II-restricted TCR transgenic mice with a positively
selecting MHC background when compared with that of the mice with a
non-selecting MHC background. IMT-1+ DP thymocytes were also decreased in
TCR transgenic mice in which negative selection occurs. When DP thymocytes
in H-Y TCR transgenic mice were stimulated with CD3epsilon mAb in vitro as
well as in vivo, the expression of IMT-1 on DP thymocytes was decreased.
Furthermore, the expression of IMT-1 on DN thymocytes from RAG-2-/- mice
was drastically reduced when CD3epsilon mAb was challenged in vivo. These
results suggest that the expression of IMT-1 on DP or DN thymocytes is
down-regulated by stimulation through TCR as well as pre-TCR. Taken
together, these results show that IMT-1 is a unique surface marker which
exquisitely separates pre-selected thymocytes from post-selected
thymocytes.
ARTICLES
Immature thymocyte antigen-1: a novel thymocyte marker discriminating pre- and post-selected thymocytes
Department of Immunology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Japan.
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