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T‐Cell Receptor Jβ Gene Segment Usage in Immature and Mature Human Thymocytes
Author(s) -
JEDDITEHRANI M.,
HODARA V.,
ESIN S.,
GRUNEWALD J.,
WIGZELL H.,
ANDERSSON R.
Publication year - 1995
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1995.tb03679.x
Subject(s) - biology , gene , receptor , microbiology and biotechnology , immunology , genetics
Immature double positive (DP, CD4 + CD8 + ) and mature single positive (SP, CD4 + CD8 − and CD4 − CD8 + ) human thymocytes from nine thymi were analysed for their complete patterns of relative TCR Jβ multigene member usage in relation to six rearranged Vβ family exons (Vβ 5.1, 6.1–3, 8, 9, 12 and 18). Each sample tested contained mRNA transcripts corresponding to all potential Vβ(Dβ)Jβ combinations. Individual Jβ gene segments were expressed in a similar, highly non‐random manner both in SP and DP thymocytes, irrespective of original genomic position of the individual associated Vβ exon. In addition, ranges of family usage and frequency of individual over‐representations of Jβ gene segments, as determined in DP and SP thymocyte populations, displayed no significant differences. Upon comparison of DP and SP thymocytes, however, a discrepancy in one aspect of Jβ gene utilization was established: decreasing Jβ family 1/ Jβ family 2 ratios were determined to be positively correlated with increasing maturity of thymocytes, a condition further supported by data previously obtained from studies of PBL T cells. At the individual Jβ gene level, the observed gradual modification of the relative family usage can largely be explained by a significant shift from a higher Jβ 1.1 /Jβ 2.7 ratio in DP to a higher Jβ 2.7/Jβ 1.1 ratio in SP thymocytes. Altogether, the present results imply that selectional processes in the thymus appear to have only minor consequences on the distribution pattern of expressed Jβ exons. Hence, the disproportionate pattern of TCR Jβ gene usage seems to be established mainly at the recombinatorial level followed by minor adjustments during thymic and post‐thymic events.