Description
Lymphocyte function associated antigen 1, also known as CD18, is a protein that in humans is encoded by the ITGB2 gene. It is an integrin protein that belongs to the class of cell membrane glycoproteins. The beta-2 integrin chain gene is designated ITGB2 and the leukocyte antigen has been designated LFA-1/CD18. The expression of LFA-1 is increased in lymphoblastoid cells from persons with Down syndrome, consistent with the location of the gene on chromosome 21. In humans lack of LFA-1 causes Leukocyte Adhesion Deficiency, a disease defined by a lack of leukocyte extravasation from blood into tissues. Although the protein is expressed on the cell surface at normal levels and is capable of function following extracellular stimulation, it could not be activated via the 'inside-out' signaling pathways