Figure 3.

Lymph node (LN) granulomatous lesions also express carboxypeptidase-M (CPM). (a₁–a₃) Serial cryosections from fresh native LN sarcoidosis (a₁) were used for in situ laser microdissection of epithelioid cells (EPCs) from rest of the inflammatory cells (holes in a₂ represent the arrow-indicated EPC clusters of a₁ after removal). The EPCs (n=3) were than collected and analyzed for CPM-mRNA in the function of reference markers using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) analyses (a₃). Normalized to cyclophilin, CPM transcript is found the most prominent in EPCs compared with CD86, MRC1, and PPARγ macrophage and dendritic cell markers. Inset shows the positive immune-staining for CPM-protein in EPCs obtained from the same specimen. (b and c) Granulomatous lymphadenitis exhibiting positive staining for CPM in EPCs. Note that cat-scratch disease (b) shows suppurative necrosis (black asterisk), and arrows point to palisade EPCs with CPM positivities (light purple cells). In toxoplasmosis (c), CPM⁺ EPCs are obvious (purple cells). (d) As shown in tumor-associated reactive lymphadenitis, epithelioid cells selectively express CPM, as opposed to CD68 labeling. Note that the small framed regions representing the same microscopic field shows more prominent CPM staining compared with CD68 image (lower right, digitally magnified).