Postnatal development of T lymphocytes in a novel X-linked immunodeficiency disease.

We previously reported an X-linked combined immunodeficiency disease (CID) characterized by immune deficiencies and complicating infections that were more moderate than those found in severe CID (SCID). Since other unstudied males in the family died in infancy, we questioned whether this T cell defect was more profound in early life. Subsequently, the development of blood T cells in an affected newborn male was examined. T cells were virtually undetectable at 48 hr. Over the next several months, CD4+ T cells (principally CD45RO+) rose to levels similar to those found in older affected males, but CD8+ T cells developed more slowly and never attained levels found in other affected males. Thus, this disease in early life mimics SCID and may pose a higher risk of fatal infections to affected individuals during that period. Finally, we speculate that the genetic defect may disrupt intrathymic development or selection of T cells.