Flow Cytometric Analysis of T Cell Vβ Repertoire in Common Variable Immunodeficiency Patients with TACI Mutations

Objective: TCR (T Cell Receptor) which is expressed on T cells is responsible for recognizing antigens presented by HLA molecules of the APCs (Antigen Presenting Cells) and initiation of the immune response. It has been reported that TACI (Transmembrane activator and calcium modulating cyclophilin ligand interactor) mediates the interaction of B cells and dendritic cells which are both responsible for the processing of T cells.
Materials and Methods: In this study, 24 TCRVβ clones were analyzed by using multiparametric flow cytometry in seven patients with TACI mutation [two homozygous (c.310T> C) five heterozygous (c.310T> C, c.226G> C, c.260T> A)], four CVID (Common Variable Immunodeficiency) patients who had not TACI defect (non-TACI) and five healthy controls. In this study group, serum Ig levels and infection history, CD4+ and CD8+ cell percentages, and HLA profiles were investigated.
Results: Increased TCRVβ13.2 clone was observed in patients with TACI defects unlike control individuals and non-TACI-CVID patients (p=0.02). We found that there was a statistically significant decrease in TCRVβ8 clone (p=0.012) in TACI deficient CVID patients and non-TACI-CVID patients compared to control individuals. TCRVβ20 clones in non-TACI-CVID patients were decreased compared to TACI-CVID patients and control individuals (p=0.009). Decreased TCRVβ8 was also associated with TACI deficient CVID patients.
Conclusion: Further studies and large cohorts are needed to understand the relationship between TCRVβ8, TCRVβ13.2, and CVID with TACI mutations.