Idiopathic CD4 T Cell Lymphocytopenia: A Case of Overexpression of PD-1/PDL-1 and CTLA-4

• Main Authors: Gaurav Kumar, Heidy Schmid-Antomarchi, Annie Schmid-Alliana, Michel Ticchioni, Pierre-Marie Roger
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Infectious Disease Reports
• Subjects: Idiopathic CD4 T cell lymphocytopenia; T cell; co-stimulatory molecules; PD-1; PDL-1; CTLA-4
• Online Access: https://www.mdpi.com/2036-7449/13/1/9

Idiopathic CD4 T cell lymphocytopenia (ICL) is a rare entity characterized by CD4 T cell count of <300 cells/mm³ along with opportunistic infection for which T cell marker expression remains to be fully explored. We report an ICL case for which T lymphocyte phenotype and its costimulatory molecules expression was analyzed both ex vivo and after overnight stimulation through CD3/CD28. The ICL patient was compared to five healthy controls. We observed higher expression of inhibitory molecules PD-1/PDL-1 and CTLA-4 on CD4 T cells and increased regulatory T cells in ICL, along with high activation and low proliferation of CD4 T cells. The alteration in the expression of both the costimulatory pathway and the apoptotic pathway might participate to down-regulate both CD4 T cell functions and numbers observed in ICL.