Immunology keratinocytes

Atopic dermatitis is an inflammatory condition with genetic, environmental, and immunologic mechanisms. Many immune cells have demonstrated abnormalities, including Langerhans cells, monocytes, macrophages, lymphocytes, mast cells, and keratinocytes. 

It was proved that at non-toxic doses, PPD induces intercellular adhesion molecule-1 (ICAM-1) expression on the keratinocytes [16]. These results were consistent with the view that oxidative stress may be an essential part of the pre-immunological phase in the induction of the allergic contact dermatitis by PPD [16]. 

Finally, cell culture studies are often used to assess direct cutaneous toxicity to skin cells such as keratinocytes. As discussed above, this can be used to define if a potential topical chemical that penetrates the skin can cause epidermal cell dysfunction. However, systemically administered chemicals can also distribute to skin and modify keratinocytes cell function. Damage to skin, especially if the mechanism of action is immunological, does not require topical exposure. 

Keratinocyte apoptosis has been observed not only during a number of biological processes, such as epidermal differentiation, but also in certain skin diseases in which the epidermis is the target of immunological cytotoxicity [47,48]. 

The complexity of skin may be better understood by its structure, the various strata epidermis is waterproof and acts as a barrier to infection dermis has the appendages of the skin hypodermis has the subcutaneous adipose tissue. Epidermis comprises the physical, the chemical/ biochemical [antimicrobial, innate immunity], and the acquired immunological barriers. The main cells in epidermis are keratinocytes, melanocytes, and Langerhans and Merkel cells. The dermis consists of connective tissue, and it is connected to the epidermis by a basement membrane. It contains nerve endings, hair follicles, sweat glands, sebaceous glands, apocrine glands. 

---