Characterization of t cell phenotypes in children and adults with common variable immune deficiency

Background: Common variable immune deficiency (CVID) is primarily a B cell disorder involving low immunoglobulin levels, defective specific antibody production and susceptibility to sino-pulmonary infections. Recent studies have implicated T cells in the pathogenesis of CVID. Our objective was to determine whether absence of normal B cells affects T cell development in patients with CVID, and to characterize T cell phenotypes in children and adults with CVID.

Methods: As part of CPRIMES (Canadian Primary Immunodeficiency Evaluation Study) project, we recruited eight children and ten adults with CVID that were followed at the immunology clinics of the Montreal General Hospital and the Montreal Children’s Hospital respectively. These patients were compared with healthy controls comprised of thirteen children and ten adults. T cell phenotype was determined with FACSCalibur and CellQuest Pro software. The Wilcoxon Rank Sum test analysis was used for statistical analysis.

Results: Total lymphocyte count as well as total CD3 lymphocyte numbers were decreased in children with CVID compared to healthy controls. T cell subsets, including memory CD4+CD45RO+ cells and naïve CD4+CD45RA + cells, were also significantly decreased. Children with CVID had lower ratios of naïve to memory cells. In adults there were no substantial differences between patients and controls.

Conclusions: CVID has been considered a disease primarily of B cells but the consequences of this disease in T cells, specifically activation and proliferation, is not well defined and little data is available on the associated functional T cell impairment. Our data shows T cell deficits in childhood CVID that are not apparent in the adult form of the disease. The natural history of childhood versus adult onset CVID requires better definition and further investigation.