What is the role of Langerhans cells in the skin?

Langerhans cells play a crucial role in providing immune defense within the skin. These specialized dendritic cells are primarily located in the epidermis and are integral to the immune system's ability to detect and respond to pathogens. They have the ability to capture and present antigens from foreign invaders, such as bacteria and viruses, to T cells in the lymph nodes. This process initiates the immune response, which is vital for protecting the body from infections and diseases.

Langerhans cells also help in the maintenance of skin homeostasis, working alongside other immune cells to ensure a balanced immune response, thereby preventing both overreactions that could lead to allergies or autoimmune diseases and underreactions that could allow infections to proliferate.

The other roles described in the choices pertain to different types of skin cells. For instance, keratinocytes are responsible for producing keratin, a key protein that contributes to the skin's protective barrier. Sebaceous glands produce oil (sebum) to lubricate the skin, while temperature regulation is primarily managed by sweat glands and blood vessels in the dermis. Thus, Langerhans cells distinctly focus on immune defense within the integumentary system.