CD79 consist of two proteins, CD79a (mb-1) and CD79b (B29). CD79a recognizes the Ig-alpha protein, and CD79b recognizes the Ig-beta protein of the B-cell antigen component of the B lymphocyte antigen receptor. The expression of CD79 precedes immunoglobulin (Ig) gene, heavy-chain gene rearrangement and CD20 expression. In precursor B cells, the CD79 protein chains are already expressed in the cytoplasm (CyCD79). Surface expression of CD79 begins at the pro-B cell stage and persists throughout the B-cell differentiation, and continues presents on plasma cells. CD79a is an excellent marker for identification of normal and neoplastic B lymphocytes. This CD79a antibody has been validated by the 9th International Conference on Human Leukocyte Differentiation Antigens (HLDA9).