CD68 is an antigen directed against human macrophages. Of the three epitopes in commercial use, we have
found that PG-M1 is preferable to HAM56 or KP1. PG-M1 appears to be the most specific for macrophages
although not necessarily the most sensitive. We find that protease digestion enhances staining. We have
had good results with either formalin or B5-fixed material in decalcified material.
In our hands, KP1 is the least reliable of the three epitopes, since it stains the majority of AMLs from
M1-M5. HAM56 is a little better (Manaloor et al, 2000). However, KP-1 may be useful to identify mast cells
and mast cell proliferations in bone marrow. CD68 may stain non-hematopoietic malignant cells (e.g.
melanoma) metastatic to the bone marrow .
- Falini B, Flenghi L, Pileri S, Gambacorta M, Bigerna B, Durkop H, et al. PG-M1: a new monoclonal
antibody directed against a fixative-resistant epitope on the macrophage-restricted form of the CD68
molecule. Am J Clin Pathol 1993;142:1359.
- Manaloor, E. et al: Immunohistochemistry can be used to subtype acute myeloid leukemia in routinely
processed bone marrow biopsy specimens. Comparison with flow cytometry. Am J Clin Pathol. 2000 113:814-22.