Early development of immunity in diGeorge syndrome.

BACKGROUND

diGeorge syndrome is a relatively common congenital disorder with developmental defects, including hypoplasia or pathologic migration of the thymus, associated with deletion of contiguous genes on chromosome 22. We prospectively followed a cohort of children with confirmed 22q11.2 deletion.

MATERIAL/

METHODS

One to six repeated examination were performed in 13 boys and 21 girls, age 4 days to 19 years. Due to the proposed role of the thymus in T lymphocyte selection, we studied T lymphocytes and their function, and also the presence of double positive CD4+CD8+ and gamma/delta T lymphocytes in peripheral blood.

RESULTS

A low number of T lymphocytes was detected in the majority of patients before the age of 2 years. Both spontaneous and PHA-induced proliferation were unexpectedly higher than in normal samples from children <2 years old. Both T cell numbers and function normalized thereafter in the majority of patients. Double positive T cells were detected in one boy, together with transient positivity of antinuclear antibodies. Gamma/delta T cells were greater than 5% in 21% of the children. In our 5-year prospective study we have not yet observed serious clinical signs of immunodeficiency or autoimmunity in these patients, except for repeated respiratory infections.

CONCLUSIONS

All patients classified as partial diGeorge syndrome presented with delayed but gradual development of immune function against a background of impaired support by the thymus.