Hr. Collard et al., Possible extrathymic development of nonfunctional T cells in a patient with complete DiGeorge syndrome, CLIN IMMUNO, 91(2), 1999, pp. 156-162
Complete DiGeorge syndrome is characterized by the clinical triad of cardia
c malformation, hypocalcemia and T cell immunodeficiency due to congenital
athymia. We describe an infant with complete DiGeorge syndrome who at prese
ntation had no circulating T cells detectable by flow cytometry. The patien
t spontaneously developed circulating T cells but these cells did not proli
ferate in response to mitogens. The T cell receptor V beta repertoire was s
everely restricted. All T cells were host, not maternal, as assessed by flu
orescent in situ hybridization evaluation of 22q11 hemizygosity. At autopsy
, this patient had no grossly detectable thymus tissue and no microscopic e
vidence for thymopoiesis. These findings suggest that clearance of T cells
in infants with complete DiGeorge syndrome may represent oligoclonal expans
ions of a small number of T cells that may have matured extrathymically and
which do not respond in vitro to mitogen stimulation. (C) 1999 Academic Pr
ess.