Anti-vimentin auto-antibodies contribute to chronic allograft nephropathy. They exist in sera of end-stage renal disease patients on hemodialysis (ESRD) already before renal transplantation. We found recently that a 49 kDa vimentin fragment is increased in lymphocytes of ESRD patients which is presented on the cell surface. In vitro studies showed that such a fragment is formed during apoptosis by active caspase-3. We hypothesized that vimentin degradation in leukocytes of ESRD patients correlates to caspase-3 activation in vivo. Lymphocytes and monocytes were isolated from ESRD patients and from healthy volunteers and analyzed for vimentin expression and caspase-3 activation. In addition, apoptosis was induced in vitro and quantified by flow cytometry. ESRD monocytes have shown only the full length 60 kDa vimentin isoform. ESRD lymphocytes, however, showed in addition a strongly increased expression of the 49 kDa vimentin in all samples. Caspase-3 activation was found in 60% of ESRD lymphocytes and 66% of ESRD monocytes but not in healthy volunteers. UV-mediated induction of apoptosis was not associated with vimentin degradation. These experiments could confirm increased vimentin degradation in ESRD lymphocytes. However, we could not validate any correlation to apoptosis.
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