Exploring the role of antigen presenting cells in male genital tract.

Antigen presenting cells (APCs) are a critical mediator between innate and adaptive immune response. APCs have diverse functions in physiological and pathological conditions, such as maintenance of tissue homoeostasis, prevention of autoimmunity and defence against pathogenic microorganisms and cancer cells. Dendritic cells (DCs) and macrophages (Mϕs) are "professional" APCs that internalise and process allo- and autoantigens; then, resulting peptides are exhibited together with major histocompatibility complex (MHC) molecules expressed at the cell surface. MHC-antigen complexes are presented to "naïve" T cells, thereby stimulating proliferation and differentiation of effector and regulatory T cells. The aim of this review was to summarise current understanding of DCs and Mϕs in testis and epididymis. Male reproductive tract environment is characterised by contradictory needs for tolerance against autoantigenic germ cells that appear after the establishment of central tolerance, and the capacity to mount pro-inflammatory innate immune responses against a wide array of sexually transmitted pathogens. Therefore, exploration of the role of APCs in male reproductive organs is helpful to understand mechanisms of male infertility associated with disruption of the delicate equilibrium between immune privilege and inflammation.