The innate reaction of the human skin lymphatic system to foreign and self-antigens.

The skin lymphatic system is the constitutive anatomical organization of the innate immune system. It reacts immediately to penetrating foreign antigens and presents them to the organized lymphoid tissue, where subsequently the adaptive immune response develops. Both phylogenetically and ontogenetically, defense mechanisms ascribed to the lymphatic system developed earlier than the nutritive function of blood elements. Resident and migrating immune cells, regulatory proteins, neuroregulatory factors, complement components, coagulation factors, and antimicrobial peptides react immediately to foreign antigens. Moreover, they most likely participate in elimination of shed autoantigens. Thus far, the knowledge of specific events and mechanisms operative in the innate response is still in a premordial stage. Further studies will elucidate not only how we immediately recognize what is nonself and react to it but also learn more about evolution of local immune memory in the immune and parenchymatous cells.