Keratinocytes, the predominant cells of the epidermis (the outer layer of skin), are primarily produced in the basal layer, also known as the stratum basale. This is the deepest layer of the epidermis.
The Basal Layer: The Birthplace of Keratinocytes
The basal layer is a remarkable area of continuous cell division and renewal. Within this layer reside keratinocyte stem cells, which are responsible for the constant production of new keratinocytes. These new keratinocytes then migrate upwards through the different layers of the epidermis, gradually differentiating and maturing as they ascend. During this process, they undergo significant changes in morphology and begin producing keratin, a tough, protective protein, along with other important substances like cytokines, growth factors, interleukins, and antimicrobial peptides (AMPs).
Keratinocyte Production and Function: A Deeper Dive
- Keratin Production: As keratinocytes move upwards, they produce increasing amounts of keratin, contributing to the skin's strength and barrier function.
- Antimicrobial Peptide Production: Keratinocytes play a crucial role in the skin's immune defense by producing AMPs, which help fight off infection. These peptides can even activate other immune cells, like plasmacytoid dendritic cells (pDCs).
- Cytokine Production: Keratinocytes are not just structural cells; they also act as active participants in the immune response. They produce various cytokines, influencing inflammation and other immune processes. In fact, their diverse cytokine production has led to them being termed "cytokinocytes."
- Vitamin D Production: The skin plays a vital role in vitamin D synthesis, and keratinocytes participate in this process.
The continuous production of keratinocytes in the basal layer ensures the constant renewal of the epidermis, maintaining its integrity and protecting the body from external damage.
