Gene-expression analysis revealed a marked upregulation of IL-2, IFN-γ, and TNF-α at 72 h, indicating a predominant Th1-type pro-inflammatory response, while IL-4, IL-6, and IL-10 remained stable or slightly downregulated.<h4>Conclusions</h4>These findings provide unprecedented evidence that feline macrophages activate a Th1-like cytokine pattern following in vitro infection with L. infantum. Here, IL2 is linked to infection.