[1518] CD68 vs. CD163, Which Is More Sensitive and Specific in Various Brain Lesions

A Treml, S Bannykh, X Fan. Cedars Sinai Medical Center, Los Angeles, CA

Background: CD68, also called KP1 is a 110-kD glycoprotein localizing to lysosomes and endosomes. It is highly expressed by monocytes and tissue macrophages. CD163 (scavenger receptor cysteine-rich type 1 protein M130 precursor) is a hemoglobin/haptoglobin scavenger receptor present on macrophages and monocytes. Two types of phagocytic cells are recognized within the central nervous system (CNS): innate microglial cells (microglia) and blood borne macrophages. Antibody to CD68 is used as a marker of both blood-borne as well as microglial cells. Less is known about the expression of CD163 in macrophages and microglia in various pathologic conditions in the CNS. The aim of this study is to compare and contrast immunoreactivity of CD68 and CD163 and to determine which antibody is more specific and sensitive in detecting macrophages and microglia in various CNS lesions.
Design: Immunostaining for CD68 and CD163 was performed on formalin-fixed paraffin embedded tissue. Forty-three cases were selected which included normal brain controls (autopsy cases without apparent CNS lesions, 10 cases), cerebral acute and subacute infarctions (10 cases), glioblastoma multiforme (10 cases), brain tissue adjacent to variety of tumors (9 cases), and demyelinating diseases (4 cases).
Results: In nearly all cases, CD163 showed a much stronger plasma membrane associated signal (3+) with a clean background, which allowed an easier visualization of reactive cells. In contrast, staining with the dilution of CD68 optimized for hematologic pathology diagnosis is consistently weaker than that of CD163 for both macrophages and microglia (1-2+). Further tittering of CD68 antibody with comparable sensitivity to CD163 (dilution from 1:20,000 to 1:2500) showed a higher background with nonspecific reactivity in endothelial cells, smooth muscle cells, and granular background staining.
Conclusions: This study shows that CD163 is superior in both sensitivity and specificity than CD68 in surgical neuropathology. CD163 consistently displayed strong membranous staining pattern outlining both macrophages and microglia with a clean background, which can be easily visualized. Although neither of the stains could be used to differentiate microglia from a blood borne macrophages (both stain macrophages and microglia), two populations can be readily separated based on their immunostaining patterns (round or ovoid plasma membrane pattern for macrophages vs. granular, stellate staining pattern for microglia. Therefore, we recommend CD163 should be the first choice for CNS lesions.
Category: Neuropathology

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 206, Tuesday Morning