CD117 (c-KIT)
Immunohistochemistry with an antibody reactive with the c-KIT encoded tyrosine kinase receptor protein
(CD117) allows accurate detection of mast cells in paraffin sections of bone marrow biopsies (Natkunam &
Rouse, 2000). In addition to c-KIT, a new monoclonal antibody specific for chymase that should prove
valuable in studying mast cells, has also been recently produced (Buckley et al, 1999). An anti-tryptase
antibody is also available. We do not have direct experience with either reagent.
By flow cytometry CD117 antigen shows a high specificity for AML, independently upon FAB classification, and
represents a reliable marker in characterizing the differentiative degree of the monocytic blasts (M5a
positive, M5b negative) Unfortunately, paraffin section immunohistochemistry for CD117 fails to identify
positive staining in myeloblasts. This "false negative" result may be due to the relatively weak expression
of c-KIT in myeloblasts as compared with mast cells, combined with the inhibitory effect of acid
decalcification.
References
- Arber et al: Paraffin section detection of the c-kit gene product (CD117) in human tissues: value in
the diagnosis of mast cell disorders. Hum Pathol. 1998 May;29(5):498-504.
- Buckley et al: The detection of mast cell subpopulations in formalin-fixed human tissues using a new
monoclonal antibody specific for chymase. J Pathol. 1999;189:138-43.
- Natkunam et al: Utility of paraffin section immunohistochemistry for C-KIT (CD117) in the differential
diagnosis of systemic mast cell disease involving the bone marrow. Am J Surg Pathol. 2000;24:81-91.
- Nomdedeu et al: Enhanced myeloid specificity of CD117 compared with CD13 and CD33. Leuk Res. 1999;
23:341-7.
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