We aimed to define thymic output and characterize immune function in a cohort of patients with molecularly defined CHH with and without associated clinical immunodeficiency.
We studied the distribution of B and T lymphocytes (including recent thymic emigrants), in vitro lymphocyte proliferation, cell cycle, and apoptosis in 18 patients with CHH compared with controls.
Patients with CHH have a markedly reduced number of recent thymic emigrants, and their peripheral T cells show defects in cell cycle control and display increased apoptosis, resulting in poor proliferation on activation.
These data confirm that RMRP mutations result in significant defects of cell-mediated immunity and provide a link between the cellular phenotype and the immunodeficiency in CHH.