SC5 mAb Represents a Unique Tool for the Detection of Extracellular Vimentin as a Specific Marker of Sézary Cells

Abstract

Circulating malignant Sézary lymphocytes result from a clonal proliferation of memory/activated CD4+CD45RO+ T lymphocytes primarily involving the skin. Recently, the CD158k/KIR3DL2 cell surface receptor has been identified to phenotypically characterize these cells. We previously described a mAb termed SC5 that identifies an unknown early activation cell membrane molecule. It is expressed selectively by T lymphocytes isolated from healthy individuals upon activation, and by circulating Sézary syndrome lymphocytes. In addition, we found that SC5 mAb was reactive with all resting T lymphocytes once permeabilized, indicating that SC5 mAb-reactive molecule might present distinct cellular localization according to the T cell activation status. In this study, we show for the first time that SC5 mAb recognizes the intermediate filament protein vimentin when exported to the extracellular side of the plasma membrane of viable Sézary malignant cells. We demonstrate that SC5 mAb is unique as it reacts with both viable malignant lymphocytes and apoptotic T cells. As vimentin is also detected rapidly at the cell membrane surface after normal T lymphocyte activation, it suggests that its extracellular detection on Sézary cells could be a consequence of their constitutive activation status. Finally, as a probable outcome of vimentin cell surface expression, autoantibodies against vimentin were found in the sera of Sézary syndrome patients.

Senescent cells expose and secrete an oxidized form of membrane-bound vimentin as revealed by a natural polyreactive antibody

“…3D). Notably, dot-like arrangements of vimentin were observed in untreated NDFs, resembling a pattern previously published (40), the vimentin detected in senescent cells appeared to occupy a larger and more prominent swath of the cell surface (Fig. 3D).…”

“…In addition to playing a fundamental role as an intermediate filament in cytoskeletal assemblies, vimentin has been shown to associate with the nucleus and cell membranes of various cell types (37)(38)(39)(40)(41)(42)(43). Because 9H4 recognizes senescent cells by SACE analysis, which is an assay that requires robust antibody interactions with cell-surface antigens, we performed a cellular fractionation experiment to determine if vimentin was enriched on the surface of senescent NDFs.…”

Vimentin and the K-Ras-induced actin-binding protein control inositol-(1,4,5)-trisphosphate receptor redistribution during MDCK cell differentiation.

“…Neither of them was supposed to react with the deletion mutant. Indeed, on the one hand, the rabbit antibody (clone EPR3776) was raised against a synthetic peptide corresponding to the Cterminus of human vimentin that is missing in VimDN-GFP; on the other hand, the mouse antibody (clone V9) has been reported to detect a truncated form of vimentin, lacking the first 138 amino acids (Huet et al, 2006), suggesting that the recognized epitope is also located in the C-terminal part of the molecule. Cells were processed for immunofluorescence microscopy 7 (like in the siRNAs experiments) or 10 days after plating (to exclude incomplete differentiation).…”

Cutting Edge: Selective Expression of Inhibitory or Activating Killer Cell Ig-Like Receptors in Circulating CD4+ T Lymphocytes

“…Reverse transcription was performed using an oligo-dT (12)(13)(14)(15)(16)(17)(18) primer (Invitrogen Life Technologies) and the PowerScript reverse transcriptase (BD Clontech). Specific primers for the amplification of KIR2DL2, KIR2DL3, and KIR2DS2 cDNA, as well as amplification conditions, were as described previously (13).…”