Epstein Barr Virus (EBV) Latent Membrane Protein 1 (LMP-1) Regulates Functional Markers in Intermediate and Non-Classical Monocytes.

: The Epstein-Barr virus (EBV) infects more than 90 percent of the human population. In pediatric patients, the innate immune response against EBV primary infection plays a key role. Monocytes and macrophages can have distinct functions depending on the microenvironment surrounding them. At least three monocyte subpopulations can be differentiated depending on membrane protein expression: classical (C, CD14++CD16-), intermediate (I, CD14++CD16+), and non-classical (NC, CD14+CD16++). They also modulate T and B lymphocyte activation/inhibition through the expression of costimulatory molecules such as CD80, CD86, and PD-L1. Yet, little is known about monocytes' role in EBV infection. : Peripheral blood and tonsil biopsies of EBV primary infected (PI) patients, healthy carriers (HCs), and patients undergoing reactivation (R) were studied. : Classical monocytes prevailed in all infectious statuses. Tonsillar CD163 positively correlated with CD163 expression in NC monocytes in HCs. PD-L1+ cells in the tonsil positively correlated with PD-L1 expression in NC monocytes. LMP-1 viral latent protein presented a positive correlation with PD-L1, CD163, and CD206 expression in the NC subpopulation. : Our results evidence the predominant role of I and NC monocytes' response against EBV infection. Furthermore, the viral oncoprotein LMP-1 could be involved in the expression of regulatory proteins in I and NC monocytes.