Lymphocyte Diversity in a 9-Year-Old Boy with Idiopathic CD4+ T Cell Lymphocytopenia

Since CD4+ lymphocytopenia can be caused by disturbed thymic T-cell maturation, we investigated the T-cell subsets of a 9-year-old boy fulfilling the diagnostic criteria for CD4+ lymphocytopenia in a follow-up period of 4 years. We found (I) reduced CD45RA expression, (II) enhanced CD45RO expression and (III) a significant increase in gamma delta TCR-bearing T cells. An accelerated apoptosis (11%) was observed in the CD45RO+, but not CD45RA+ subset. These findings provide evidence that a disturbed thymic T-cell maturation process might play a role in the pathogenesis of CD4+ lymphocytopenia.