BCL2

The BCl-2 molecule is an oncogene product (oncoprotein) blocking apoptotic cell death1. In lymphoid tissues Bcl-2 is expressed by mantle zone B-cells and all effector T-cells, while germinal centre B-cells lack this protein at an immunodetectable level. Bcl-2 immunoreaction results in an eccentric cytoplasmic signal since it is localised in the nuclear envelope, endoplasmic reticulum and mitochondrial membrane in positive cells. The up-regulation of BCl-2 expression in lymphoid nodular structures is a specific feature of most follicular lymphomas resulting from the t(14;18) chromosomal translocation when the BCl-2 gene is inserted into juxtaposition to the highly active IgH gene2