Immunologic defects in 22q11.2 deletion syndrome.
BACKGROUND
22q11.2 Deletion syndrome, the most common congenital chromosome deletion syndrome, is associated with developmental defects including cardiac abnormalities and hypoplasia or abnormal migration of the thymus. These patients have variable defects in T-cell immunity with an increased incidence of infection and autoimmune disease.


OBJECTIVE
To investigate the immunologic constitution of children with 22q11.2 deletion syndrome.


METHODS
We characterized the immunologic constitution of 27 children with 22q11.2 deletion syndrome and 54 healthy controls by flow-cytometric analysis of peripheral blood lymphocyte populations.


RESULTS
Patients exhibited decreased T-cell numbers, although the normal age-related decrease in T-cell numbers was slower than in healthy children. There was a significant decrease in FoxP3(+) natural regulatory T (nTreg) cells with a strong correlation between nTreg cells and recent T-cell emigrants from the thymus, suggesting a link between the nTreg cell population and thymic function. Although total B-cell numbers were unaffected, patients showed a significantly decreased proportion of memory B cells in the B-cell pool.


CONCLUSIONS
Lower nTreg cells in patients suggest that the generation and maintenance of these cells in children is related to thymic function. In addition to T-cell abnormalities classically seen in this syndrome, subtle defects in the B-cell compartment may also be seen.
McLean-Tooke
Andrew
A
Department of Immunology, Royal Victoria Infirmary, Newcastle-Upon-Tyne, United Kingdom. andymctooke@yahoo.co.uk
Barge
Dawn
D
Spickett
Gavin P
GP
Gennery
Andrew R
AR
D001402:B-Lymphocytes / Q000276:immunology*; D002872:Chromosome Deletion; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D004062:DiGeorge Syndrome / Q000276:immunology*; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000097:blood; D007694:Killer Cells, Natural / Q000276:immunology; D018655:Lymphocyte Count; D008297:Male; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
D007136:Immunoglobulins