In mice with a type of lymphoma, giving the peptide thymosin‑alpha‑1 (or a normal mouse thymus extract) made the tumor‑associated immune cells (macrophages) produce more nitric oxide, a molecule that can help kill cancer cells. This effect got even bigger when the cells were also exposed to a bacterial signal (LPS), and factors from the tumor itself seemed to boost the response. The study shows thymosin‑alpha‑1 can directly activate these immune cells, which might be useful for cancer‑related immune support, but it’s an early animal study with no human dosing guidance.

The present investigation was conducted to study the effect of thymic peptide: thymosinalpha1 (thyalpha1) on the activation of tumor associated mphi (TAM) obtained from mice bearing a transplantable T cell lymphoma of spontaneous origin designated as Dalton's lymphoma, to produce nitric oxide (NO). It was found that in vivo administration of aqueous thymic extract obtained from thymus of normal mice or thyalpha1 could activate the TAM to produce enhanced amount of NO which was further augmented on in vivo treatment of these TAM by LPS. These observations suggest that thyalpha1 could prime TAM for activation by second signal of LPS. The study also presents evidence that tumor cell elaborate factors that enhance the effect of thyalpha1 on TAM for production of NO. This is the first study to show that thyalpha1 can activate TAM directly even in the absence of LPS, and may, therefore, have clinical significance.