, Volume 81, Issue 6, pp 675-679

Proliferating cell nuclear antigen and Ki-67 immunohistochemistry in brain tumors: A comparative study

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Summary

Proliferating cell nuclear antigen (PCNA) is a 36-kDa DNA polymerase-σ auxiliary protein which accumulates in the nucleus during S phase of the cell cycle. Immunohistochemical labeling indices (LI) of PCNA and Ki-67 were compared using an avidin-biotin complex method on frozen sections of 27 nervous system tumors, 3 normal cerebral cortices, and 3 peripheral nerves. In glial tumors, PCNA and Ki-67 LI increased with increasing tumor grade (Daumas-Duport system). In 5 low-grade glial tumors, PCNA and Ki-67 LI were ≤1%, except for one optic nerve glioma (Ki-67 LI=6%). In 7 grade 3 astrocytomas, and 1 mixed glioma, PCNA LI were ≤1–1.5%, while Ki-67 LI were 2%–10%. In 7 grade 4 astrocytomas and 1 metastatic carcinoma, PCNA LI ranged from 6%–15% while Ki-67 LI ranged from 17%–30%. In 5 of 6 schwannomas, focally high PCNA LI (4%–65%) were noted, despite low LI with Ki-67 (≤1.6%). Scattered normal schwann cell nuclei also stained with PCNA, but normal cerebral cortex did not. These data suggest that: (1) in higher-grade gliomas, PCNA may be a more specific S-phase marker, although a less sensitive proliferation marker, than Ki-67; (2) PCNA LI do not distinguish low-grade gliomas from grade 3 astrocytomas; (3) in schwannomas, PCNA may not reflect proliferative activity since it seems to react with an epitope present in normal schwann cells; and (4) the variable PCNA staining pattern introduces greater difficulties in cell counting than with Ki-67. These factors may limit the use of this anti-PCNA antibody in evaluating nervous system tumors.

Supported in part by an American Cancer Society Career Development Award (ADT). Presented in part at the 66th meeting of the American Association of Neuropathologists, San Francisco, CA, June 14, 1990