Integrin, alpha E (ITGAE) also known as CD103 (cluster of differentiation 103) is an integrin protein that in human is encoded by the ITGAEgene. CD103 binds integrin beta 7 (β7– ITGB7) to form the complete heterodimeric integrin molecule αEβ7, which has no distinct name. The αEβ7 complex is often referred to as "CD103" though this strictly refers only to the αE chain. Note that the β7 subunit can bind with other integrin α chains, such as α4 (CD49d).
The chief ligand for αEβ7 is E-cadherin, a cellular adhesion molecule (CAM) found on epithelial cells. It is probably important for T cell homing to the intestinal sites.
Tregs are important for decreasing the immune response and appear to play a crucial role in the prevention of autoimmune diseases. Tregs are defined as CD4+/CD25+/Foxp3+ cells. Some CD4+/FoxP3− cells also express CD103 and have been attributed regulatory activity. It is unclear whether the presence of CD103 on Treg cells represents a specialized feature for Treg, or Treg differentiation of IEL T cells.
^Aziz S, Fackler OT, Meyerhans A, Müller-Lantzsch N, Zeitz M, Schneider T (January 2005). "Replication of M-tropic HIV-1 in activated human intestinal lamina propria lymphocytes is the main reason for increased virus load in the intestinal mucosa". J. Acquir. Immune Defic. Syndr. 38 (1): 23–30. doi:10.1097/00126334-200501010-00005. PMID15608520. S2CID22884381.
^Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J, Vardiman JW (2008). WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (World Health Organization Classification of Tumours) (4th ed.). Geneva: World Health Organization. ISBN978-92-832-2431-0.
^Allakhverdi Z, Fitzpatrick D, Boisvert A, Baba N, Bouguermouh S, Sarfati M, Delespesse G (December 2006). "Expression of CD103 identifies human regulatory T-cell subsets". J. Allergy Clin. Immunol. 118 (6): 1342–9. doi:10.1016/j.jaci.2006.07.034. PMID17137867.
Liu YH, Chen RH, Chen WC, et al. (2010). "Disease association of the CD103 polymorphisms in Taiwan Chinese Graves' ophthalmopathy patients". Ophthalmology. 117 (8): 1645–51. doi:10.1016/j.ophtha.2009.12.037. PMID20417566.
Lesch KP, Timmesfeld N, Renner TJ, et al. (2008). "Molecular genetics of adult ADHD: converging evidence from genome-wide association and extended pedigree linkage studies". J Neural Transm. 115 (11): 1573–85. doi:10.1007/s00702-008-0119-3. PMID18839057. S2CID7036114.
Heron M, Grutters JC, Van Moorsel CH, et al. (2009). "Effect of variation in ITGAE on risk of sarcoidosis, CD103 expression, and chest radiography". Clin. Immunol. 133 (1): 117–25. doi:10.1016/j.clim.2009.06.007. PMID19604725.
Heron M, Slieker WA, Zanen P, et al. (2008). "Evaluation of CD103 as a cellular marker for the diagnosis of pulmonary sarcoidosis". Clin. Immunol. 126 (3): 338–44. doi:10.1016/j.clim.2007.11.005. PMID18182176.