PAX-5 (RBT-PAX5), RMab

Summary and Explanation

The PAX proteins are important regulators in early development, and alterations in the expression of their genes are thought to contribute to neoplastic transformation. The PAX-5 gene encodes the B-cell lineagespecific activator protein (BSAP) that is expressed at early, but not late, stages of B-cell differentiation. Its expression has also been detected in developing CNS and testis; therefore, PAX-5 gene product may not only play an important role in B-cell differentiation, but also in neural development and spermatogenesis.

PAX-5 antibody expression is not only continuously required for B-cell lineage commitment during early B-cell development but also for B-cell lineage maintenance. PAX-5 is found in most cases of mature and precursor B-cell Non-Hodgkin’s Lymphomas/Leukemias. PAX-5 is not detected in Multiple Myeloma and solitary Plasmacytoma, making it useful for such differentiation. Diffuse Large B-cell Lymphomas do express PAX-5, except for those with terminal B-cell differentiation. T-cell neoplasms do not stain with anti-PAX-5 antibody; however, there is a strong association with CD20 expression.