Characterization of the T Cell Receptor Repertoire in Patients with Common Variable Immunodeficiency: Oligoclonal Expansion of CD8+ T Cells

Common variable immunodeficiency is characterized by an impairment in antibody production of at least two immunoglobulin isotypes, and abnormalities of both B and T cells have also been described. In this study, a profound alteration of the T cell receptor repertoire was noted, especially in CD8+ T cells, in CVID patients when compared to a control group. However, the higher number of oligoclonally expanded populations seen in the patient group was not dependent on age, whereas in the control group an age-related accumulation of these populations was noted. Expansion of CD8+ CD28− T cells in these patients is strongly correlated with T cell receptor repertoire restriction. Furthermore, analysis of cytokine production showed a statistically significant increase in IFN-γ secretion in the patient group. Lastly, CD94 and perforin were expressed at increased frequencies on CD8+ T cells in the patient group when compared to the control group. We speculate that these findings support the concept that CD8+ T cells may play an important regulatory role in CVID.