Immunoregulation in the testis and its implication in fertility and infections

Abstract

The testis is designated as one of the immune previleged sites in the body and harbours a unique immunoregulatory environment, which is important for preventing an immune response against sperm antigens which otherwise are recognized as “foreign” by the immune system. The blood-testis barrier along with the unique immune cells repertoire and various immunoregulatory & immunosuppressive factors secreted by the Leydig cells, Sertoli cells and peritubular cells act in concert to maintain the tolerogenic environment in the testis. Abberations in immunotolerant mechanisms in the testis can lead to generation of anti-sperm antibodies that have an association with male infertility. It can also lead to inflammatory conditions of the male reproductive tract manifested as epididymitis and orchitis, generally due to bacterial or viral infections. In addition, non-infectious epididymitis and orchitis, having autoimmune origin have also been reported in males. While the immune privilege status of human testis protects the germ cells from an immune attack, it can also make the testis a succeptible reservoir for viruses such as human immunodeficiency virus-1, Zika virus and severe acute respiratory syndrome coronavirus-2, all of which have adverse consequences on male reproduction.