Clonal expansion of Vγ3/Vδ3-expressing γδ T cells in a HIV-1/2-negative patient with CD4 T-cell deficiency

Abstract

Immunological investigations were carried out in an HIV-1/2//HTLV-1-negative patient with CD4 T-cell deficiency (0.357-0.6 x 109/l) and expansion of γδ T cells which accounted for 26-42% of peripheral blood lymphocytes during an observation period of 3 years. Flow cytometry analyses with a panel of available Vγ/Vδ-specific monoclonal antibodies indicated that the pathologically expanded γδ population expressed Vγ2 or Vγ3 paired with Vδ 3 on the surface but lacked the expression of activation antigens such as CD38 or CD71. Cloning and sequencing of RT-PCR products obtained after amplification of cDNA with Vγ-Cγ and Vδ-Cδ specific primers confirmed the presence of a clonally expanded Vγ3/Vδ3 population in the peripheral blood of this patient. Cytotoxicity assays performed with purified γδ T cells as effectors and resting or preactivated autologous CD4 T cells as targets failed to reveal evidence for autoreactive cytotoxicity of Vγ3/Vδ3 cells as a possible mechanism of CD4 T-cell deficiency in this patient.