THE VALUE OF IMMUNOHISTOCHEMISTRY
IN THE ASSESSMENT OF BONE MARROW DISORDERS

Attilio Orazi, M.D., FRCPath. and Dennis P. O'Malley, M.D.

CD79a (HM57) CD79a is a monoclonal antibody which is reactive to a majority of B lymphocytes. It is positive in many acute lymphoblastic leukemias, in B cell lymphomas, and negative in the vast majority of T cell lymphomas. It is of value as an additional B cell marker in association with CD20 and can be of great value in cases when CD20 is negative. An antigen retrieval technique is advised. Staining is equally effective in formalin and in B5 fixative and appears resistant to decalcification. References Mason et al. CD79a: a novel marker for B-cell neoplasms in routinely processed tissue samples. Blood. 1995; 86:1453-9.