*2.1. Study Population*

Twenty healthy controls (HC) were enrolled in the study in order to investigate the induction of ERAP isoform transcription in response to common recall antigens such as influenza-antigens (flu), Lipopolisaccaride (LPS), Citomegalovirus (CMV), in addition to Aldrithiol-2 (AT-2)-inactivated R5-tropic human immunodeficiency virus-1Ba-L (HIV-AT-2) and acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inactivated virus (i-SARS-CoV-2). The Ethical Committee of the Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico approved the study (Prot. N◦0028257). All the donors signed an informed consent form, in agreemen<sup>t</sup> with the Declaration of Helsinki of 1975, revised in 2013.
