Flow cytometric analysis of TCR Vb repertoire in XXXX with 22q11.2 deletion syndrome.

@entity1 @entity404 @entity4670 @entity2279 @entity281 @entity854 @entity792 @entity2902 @entity405
In 22q11.2 deletion @entity1 , the normal decrease in T lymphocyte counts after 1-2   years is blunted such that relatively T lymphocyte numbers increase over early childhood, probably via post-thymic expansion of peripheral lymphocytes. This may leave less T lymphocyte receptor (TCR) diversity than when derived from naive thymic emigrants. We analysed TCR Vb repertoire on 27 22q11.2 chromosome deletion @entity1 . No @entity1 had @entity281 at sampling. CD3(+) @entity404 (+) recent thymic emigrants (RTEs) were identified by CD45RA and @entity2279 expression. TCR Vb repertoire was determined using four-colour flow cytometry. @entity1 and controls showed significant TCR Vb family usage differences between CD3(+) @entity404 (+) and CD3(+) @entity404 (-) T lymphocyte subpopulations. @entity4670 (  3   SD of controls) were identified in 18/27 (67%) @entity1 and 12/47 (25%) controls. In @entity1 , the magnitude of expansions was increased, with some Vb families representing 37% of the cells present in the subpopulations. There was a significant increase in frequency of abnormalities in CD3(+) @entity404 (+) (P   <   0.001) and CD3(+) @entity404 (-) T lymphocytes (P   <   0.05) in @entity1 . A total of 11/16 @entity1 had an abnormal @entity404 (+) @entity2902 (Bright) TCR Vb repertoire. There was no difference in expansions/contractions between @entity404 (+) @entity2902 (Bright) and @entity404 (+) T lymphocyte repertoires (P   =   0.575) for individual @entity1 but significant differences in expansions/contractions between @entity404 (+) @entity2902 (Bright) and @entity405 (+) T lymphocytes repertoires (P   =   0.011). There was bias in Vb usage between CD3(+) @entity404 (+) and CD3(+) @entity404 (-) T lymphocyte subsets. A total of 67% @entity1 had TCR Vb @entity854 , with a trend towards increased @entity854 with fewer RTEs, suggesting thymic output plays an important role in TCR repertoire diversity. There was no correlation between skewed repertoire and symptoms of @entity281 or @entity792 .
