Thymosin α 1 potentiates the release by CD8⁺ cells of soluble factors able to inhibit HIV-1 and human T lymphotropic virus 1 infection <i>in vitro</i>

<b><i>Background:</i></b> Thymosin α-1 (Tα1) exploits a specific action on lymphoid cells and is able to induce in peripheral blood mononuclear cells (PBMCs) a strong transcriptional response. CD8 antiviral factor activity plays a role in the control or prevention of HIV-1 infection by a non-cytolytic mechanism. The ability of Tα1 to modulate the release of antiretroviral soluble factors by CD8⁺ cells was investigated. <b><i>Methods:</i></b> Supernatants from lipopolysaccharide (LPS) stimulated CD8⁺-isolated cells treated with Tα1 were screened on <i>in vitro</i> infection of human monocyte-derived macrophages (MDMs) and PBMCs with HIV-1, and of PBMCs with human T lymphotropic virus 1 (HTLV-1). In CD8⁺ cells, as well as in PBMCs of healthy donors as from HIV⁺ individuals, a microarray analysis to assess the transcriptional response after treatment was performed. <b><i>Results:</i></b> Tα1 potentiates the release, in LPS-stimulated CD8⁺ cells, of soluble factors able to inhibit both <i>in vitro</i> HIV-1 infection of MDMs and PBMCs and <i>in vitro</i> HTLV-1 infection of PBMCs. A distinctive transcriptional profile was induced by Tα1 in PBMCs from HIV⁺ donors. <b><i>Conclusions:</i></b> These findings suggest that Tα1 would represent a re-evaluated approach to antiretroviral therapy in combination with innovative treatments and with vaccine administration.