Figure 2.

Schematic of immunosuppressive molecules that support immune privilege in the testis. SCs and LCs secrete multiple immunosuppressive factors, including activin A, TGF-β, PDL-1, Gas6, ProS and testosterone, which directly or indirectly suppress immune cell activation. Mϕ and MCs exhibit immunosuppressive properties by producing anti-inflammatory factors, such as IL-10 and TGF-β. Germ cells abundantly express FasL. Whether FasL induces apoptosis of T lymphocytes that may infiltrate the seminiferous tubules under inflammatory conditions remains unclear. FasL, Fas ligand; Gas6, growth arrest-specific gene 6; LC, Leydig cell; MC, mast cell; Mϕ, testicular macrophages; PDL-1, programmed death ligand-1; ProS, protein S; SC, Sertoli cell; TGF-β, transforming growth factor β.