What role do Langerhans cells play in the skin?

Langerhans cells are a specialized type of dendritic cell located in the epidermis, which play an essential role in the skin's immune response. Their primary function is to patrol the epidermis, monitoring for foreign pathogens such as bacteria and viruses. When they encounter these invaders, they capture and process the antigens and then migrate to the lymph nodes, where they activate T-cells and stimulate the adaptive immune system. This ability to "patrol" and signal an immune response is crucial for the skin in maintaining a protective barrier against infections.

In contrast, the other options describe functions that do not pertain to Langerhans cells. For instance, producing sweat is predominantly the role of sweat glands, while forming new skin cells is primarily the function of keratinocytes located within the epidermis. Absorbing nutrients is not a function associated with skin cells but rather with cells found in other tissues, such as the intestines. Each of these options pertains to different biological processes in the skin or body rather than the immunological function of Langerhans cells.