The interleukin-1 (IL-1) system has been suggested to be involved in the cell–cell cross talk within the testis. To identify a testicular cell source of IL-1 alpha, IL-1 beta and IL-1 receptor antagonist (IL-1ra), immature mouse Sertoli cells were isolated, purified, cultured and examined for the cellular compartment localization of these cytokines by immunohistochemical staining. Our results show that both Germ cells and Sertoli cells in unpurified Sertoli cell cultures (before hypotonic shock) and purified culture of Sertoli cells (after hypotonic shock) were stained for IL-1 alpha. The levels of this cytokine were increased in Sertoli cells when the purified cultures were stimulated with lipopolysaccharide (LPS) (5 μg/mL). However, we could not identify a positive staining for IL-1 beta when Sertoli cell cultures were stained for this cytokine, even after stimulation with various concentrations of LPS (0.1–10 μg/mL). On the other hand, immunohistochemical staining of isolated Sertoli cells without treatment with hypotonic shock (cultures containing Sertoli cells and Germ cells) for IL-1ra showed constitutive positive staining of both cell types (Sertoli cells and Germ cells). Our results, using immunohistochemical staining, may indicate the different expression of IL-1 alpha, IL-1 beta and IL-1ra in Sertoli cells. These results may suggest the involvement of IL-1 system in the autocrine and paracrine regulation of testicular cell functions.