LA JOLLA\u2014In most of the tissues of the body, specialized immune cells are entrusted with the task of engulfing the billions of dead cells that are generated every day. When these garbage disposals don\u2019t do their job, dead cells and their waste products rapidly pile up, destroying healthy tissue and leading to autoimmune diseases such as lupus and rheumatoid arthritis.\n<\/p>\n
\nNow, Salk scientists have discovered how two critical receptors on these garbage-eating cells identify and engulf dead cells in very different environments, as detailed September 7 in Nature Immunology<\/em><\/a> and September 29 in eLife<\/em><\/a>.\n<\/p>\n \nFrom left: Greg Lemke, Erin Lew, Anna Zag\u00f3rska and Paqui Gonzalez<\/p>\n Click here<\/a> for a high-resolution image.<\/p>\n \nImage: Courtesy of the Salk Institute for Biological Studies\n<\/p>\n<\/div>\n \n\u201cTo target these receptors as treatments for autoimmune disease and cancer, it\u2019s important to know exactly which receptor is doing what. And this discovery tells us that,\u201d says senior author of the work Greg Lemke<\/a>, Salk professor of molecular neurobiology<\/a> and the holder of Salk\u2019s Fran\u00e7oise Gilot-Salk Chair.\n<\/p>\n \nThe garbage-disposing cells, known as macrophages, have arrays of receptors on their surface, two of which\u2014called Mer and Axl\u2014are responsible for recognizing dead cells in normal environments and inflamed environments, respectively. Mer operates as a \u201csteady-as-she-goes\u201d receptor, clearing out dead cells in healthy tissues on a daily basis. Axl, in contrast, acts as an \u201call-hands-on-deck\u201d receptor, kicking macrophages into action in inflammatory settings that result from infection or tissue trauma. These inflamed environments have many more dead cells.\n<\/p>\n![\"\"](\"https:\/\/www.salk.edu\/wp-content\/uploads\/2014\/01\/2049-Lemke-Lab.jpg\")
<\/p>\n