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J Mirro , G Kitchingman, FG Behm, SB Murphy and RM Goorha
T cell differentiation was investigated by determining the relationship of
T cell receptor (Ti) gene rearrangement and transcription to the expression
of surface and cytoplasmic T3 antigen using blast cells from five children
with acute lymphoblastic leukemia of thymic origin. Patterns of monoclonal
antibody (MoAb) reactivity indicated that these cases were representative
of the three recognized stages (I, II, III) of human thymocyte development.
The T3 antigen, which becomes linked to the Ti to form a functional T cell
receptor complex on mature thymocytes, was expressed on the cell surface in
two cases (stage III). However, in the remaining three cases that were
surface T3 negative (stages I and II), large amounts of T3 were identified
in the cytoplasm by immunoperoxidase staining and flow cytometry. Leukemic
blasts from all five patients showed rearranged genes encoding the
beta-chain portion of the Ti heterodimer. RNA transcripts of Ti beta-chain
genes were also evident in lymphoblasts from all five cases, but
transcripts coding for the alpha-chain portion of Ti were found only in
cases that expressed T3 on the cell surface. Thus the absence of surface T3
(and presumably Ti) coincides with the absence of Ti alpha-chain RNA,
suggesting that transcription of alpha-chain genes is a critical regulatory
event in the surface expression of the Ti-T3 complex. Leukemic T cells that
rearrange and express Ti beta-chain genes but lack Ti alpha-chain messenger
RNA (mRNA) may represent a stage of differentiation analogous to pre-B
cells, where heavy-chain immunoglobulin (Ig) genes are rearranged and
expressed but light-chain Ig genes are not expressed.
This article has been cited by other articles:
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| Copyright © 1987 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
