Subjects
The diagnosis of AIN in children was based on the presence of chronic
neutropenia and positivity for antineutrophil antibodies in sera
according to the criteria published in the Nelson Textbook (21).
Antineutrophil antibody was detected using an indirect granulocyte
immunofluorescence test, as previously described (4). Table Ipresents the characteristics of 25 patients with AIN enrolled in this
study: 13 patients for the analysis of the
frequency of total Tregs and
activated Tregs (median age: 17 months, range: 7–69 months) and 17
patients for the analysis of the TCR-Vβ repertoire (median age: 20
months, range: 11–57 months). Five patients were included in both
analyses. AIN in childhood shows spontaneous resolution within a few
years without the need for treatment. Hence, these TCR repertoire assays
were performed in the middle of the neutropenic period. Parts of the
assays in some patients were performed at the end of the spontaneous
recovery from neutropenia. Treg and TCR repertoire assays were
longitudinally performed in three patients with AIN. The results of the
analyses in these patients did not show any fluctuations. Therefore, the
TCR repertoire assay was compared between patients with AIN and
age-matched control subjects. Eighteen (median age: 17.5 months, range:
4–78 months) and 22 (median age: 20 months, range: 8–49 months) heathy
children without neutropenia were also examined as age-matched control
subjects for respective analyses.
Informed consent was obtained from the guardians of patients and control
subjects, and approval for these studies was obtained from the
institutional review board.