Accumulation of CD138+ T cells in an SLE murine model
Syndecan-1 (sdc-1, CD138) is a heparan sulfate proteoglycan that
modulates multiple biological and immune activities, such as cellular
multiplication and differentiation 15. CD138, which is
also expressed in epithelial cells and other adherent cells, has been
thought to be a marker for plasmablasts and plasma cells in lymphocytes,
which have been suggested to have originated from activated B cells16, 17. CD138 has also been found on the surfaces of
CD3 expressed T cells. CD138+ T cells have also been reported to be
plasmablastic B-cell neoplasms in clinical cases 18.
However, these abnormal CD138+ cells, i.e., CD138+ T cells, have also
been identified in lupus mice; they were found to accumulate in spleens,
lymph nodes, gut, and peripheral tissues in lupus mice as their ages
increased 12-14.
CD138+ T cells mainly derive from DN T cells; a proportion of them
derives from CD4+ T cells 13, 14. The frequency at
which CD138+ T cells are derived from CD8+ T cells is negligible14. CD138+ T cells have been shown to constitute a
small fraction of cells in the spleen of non-lupus prone mice, but not
to significantly accumulate in MRL/lpr mice 14. This
indicates that Fas-deficiency results in the accumulation of CD138+ T
cells. Compared with CD138- T cells, CD138+ T cells have a lower level
of proliferation 14. Importantly, the apoptotic number
of CD138+ T cells has been shown to decrease dramatically, compared with
CD138- T cells (unpublished data by Tianhong Xie et al.). Significantly
increased levels of live cells and decreased apoptosis levels in CD138+
T cells induce the accumulation of CD138+ T cells in lupus mice, but
hyper proliferation does not 14.