Immune electron-microscopy study of the trimeric glycoprotein (CD 103) of hairy cell leukemia using the Ber-ACT8 monoclonal antibody.

We describe a method which makes it possible to study the expression of the trimeric glycoprotein (TGP, CD 103) on the surface of hairy cells (HCs) by electron microscopy (e.m.). The monoclonal antibody (mAb) Ber-ACT8 was used to identify the TGP. By testing mucosa of the small intestine, we found that a prefixation incubation with Ber-ACT8 was necessary. After isolation with a density gradient, Ber-ACT8 incubation, and fixation, the peroxidase-anti-peroxidase (PAP) method was used to make the TGP visible. The HCs showed a clearly discernible stain on their surface, a fairly constant distribution of the TGP, and a very good ultrastructural preservation. This method makes it possible to demonstrate the TGP or other unfixable antigens by e.m.