In mice, the immune‑boosting peptide thymosin‑alpha‑1 helped reverse the damage to immune cells caused by cocaine use, speeding up recovery of natural killer cells and restoring key T‑cell functions and cytokine levels.

The effects of different in vivo thymosin alpha one (T alpha 1) treatments on T-cell responses inhibited by cocaine abuse were studied. Administration during cocaine treatment promoted a faster recovery of normal natural killer (NK) cell activity after the suspension of abuse. Suspension of cocaine plus repeated T alpha 1 administrations strongly restored NK activity and, interestingly, spleen cells from mice treated with T alpha 1 during and after cocaine administration achieved a very rapid recovery and the greatest stimulation of natural cytotoxicity. This last treatment also restored the cocaine-inhibited specific T-cell response (i.e. allogeneic cytotoxic T-lymphocyte (CTL) generation) and abrogated the cocaine-induced suppression of interferon gamma (IFN-gamma), interleukin 2 (IL-2) and IL-4 production. Finally restoration and induction of thymic cellularity were significant when T alpha 1 was given during and after cocaine administration. The present investigation provides evidence for the first time that thymic hormones could be of potential value in controlling cocaine-induced impairment of T-cell-mediated immunity in the mouse.