CD1D and systemic sclerosis: Interestingly in this regard, whereas the direct IPP Vγ9+ T cell stimulator can quite efficiently activate SSc Vγ9+ T cells, zol is quite inefficient in this regard, consistent with our previous report (4, 5) Our data suggest that zol-induced decrease of CD25 expression might involve decreased binding of CD1d (presumably via their TCR) to the Vδ1+ T cells, by an unknown underlying mechanism (Figure 5).