<prompt> All are B cell marker except-CD-15CD-19CD-21CD-23  <response>: Reference :Robbins basic pathology 9th edition pg no 117:Some are the signaling molecules attached to the BCR; another example is CD21 also known as the type 2 complement receptor, or CR2, which recognizes a complement break- down product that frequently is deposited on microbes and promotes B cell responses to microbial antigens. Inter- estingly, the ubiquitous Epstein-Barr virus has cleverly evolved to use CD21 as a receptor for binding to B cells and infecting them. 