The testis is known as an immunologically privileged organ. Immune tolerance has already been established at birth when testicular germ cells (TGC) contain only stem cells or spermatogonia34. After puberty, they differentiate into spermatocytes and spermatids; the differentiation involves the expression of new molecules as spermatogenesis begins. Therefore, TGC are believed to contain various cell type-specific autoantigens which are recognized as foreign by the immune system34. The blood–testis barrier (BTB), formed by Sertoli cells, protects autoimmunogeneic TGC from any autoimmune attack34. Moreover, testicular cells express and secrete numerous immunoregulatory molecules that have important roles in the regulation of immune responses in the testes. These molecules create a regulatory system called “testicular immune privilege” and include androgens, activin, Fas ligand, protein S, and immunosuppressive cytokines such as interleukin (IL)-10, IL-35 and transforming growth factor (TGF)-β56789101112. When the BTB is functionally damaged, TGC autoantigens can pass beyond the seminiferous epithelium and create a continuous stream of AIs that are exposed to systemic immune system, often for extended periods of time3. For example, damage to BTB of testis due to infection, biopsy, torsion, or surgery in the scrotal area induces orchitis in the contralateral testis131415. Therefore, the AIs in TGC can be considered a critical target of autoimmune damage.