The CD11a* membrane antigen is carried by T lymphocytes.
It allows them, by binding to an ICAM (intercellular adhesion molecule) of endothelial cells, to cross the capillary wall and enter the epidermis. There :
- CD11a stimulates the keratinocyte's ICAM,
- the activated lymphocytes also stimulate keratinocytes.
Hence the accelerated proliferation and maturation of keratinocytes : PSORIASIS.
Efalizumab is an anti CD11a monoclonal antibody, of therapeutic value in psoriasis.