Expanded cells in monoclonal TCR-αβ+/CD4+/NKa+/CD8−/+dimT-LGL lymphocytosis recognize hCMV antigens

Recent studies suggest the potential involvement of common antigenic stimuli on the ontogeny of monoclonal T-cell receptor (TCR)–αβ+/CD4+/NKa+/CD8−/+dimT-large granular lymphocyte (LGL) lymphocytosis. Because healthy persons show (oligo)clonal expansions of human cytomegalovirus (hCMV)–specific TCRVβ+/CD4+/cytotoxic/memory T cells, we investigate the potential involvement of hCMV in the origin and/or expansion of monoclonal CD4+T-LGL. Peripheral blood samples from patients with monoclonal TCR-αβ+/CD4+T-LGL lymphocytosis and other T-chronic lymphoproliferative disorders were evaluated for the specific functional response against hCMV and hEBV whole lysates as well as the “MQLIPDDYSNTHSTRYVTVK” hCMV peptide, which is specifically loaded in HLA-DRB1*0701 molecules. A detailed characterization of those genes that underwent changes in T-LGL cells responding to hCMV was performed by microarray gene expression profile analysis. Patients with TCR-αβ+/CD4+T-LGL displayed a strong and characteristic hCMV-specific functional response, reproduced by the hCMV peptide in a subset of HLA-DRB1*0701+patients bearing TCRVβ13.1+clonal T cells. Gene expression profile showed that the hCMV-induced response affects genes involved in inflammatory and immune responses, cell cycle progression, resistance to apoptosis, and genetic instability. This is the first study providing evidence for the involvement of hCMV in the ontogeny of CD4+T-LGL, emerging as a model disorder to determine the potential implications of quite a focused CD4+/cytotoxic immune response.