Enzyme histochemistry and immunohistochemistry on biopsy specimens of pathologic human bone marrow

We have systematically investigated a variety of fixation and plastic embedding procedures and arrived at a method that allows processing of approximately 2-micron sections of bone marrow biopsies for examination by light microscopy. More importantly, this method permits the use of enzyme histochemical and immunohistochemical procedures that are rapidly becoming mandatory in the diagnosis of hematologic malignancies. Over 200 full-length bone marrow biopsy specimens were fixed in a mixture of paraformaldehyde, glutaraldehyde, and acrolein, dehydrated in acetone, and embedded in a mixture of methyl and glycolmethacrylate. All procedures were carried out at 4 degrees C. Decalcification was unnecessary. Sections 2-micron thick were cut and incubated for peroxidase, naphthol AS-D chloroacetate esterase, alpha- naphthyl butyrate esterase, acid phosphatase (with and without tartrate), or alkaline phosphatase and then examined by light microscopy. Specimens could be prepared for examination within 48 hr. This approach, which provides definitive markers for various hematopoietic cell lines in intact tissues, is invaluable when aspirated material is unavailable. It is also useful in the analysis of focal lesions of bone marrow due to inflammation or neoplasia and shows potential as an investigative tool. For example, we have discovered that early myelofibrosis is accompanied by a marked increase in the number of alkaline-phosphatase-positive reticulum cells.