CX3CR1 and systemic sclerosis: While no correlation was noted between circulating fractalkine levels and percentages of CX3CR1 expressing NK cells, CD8 T cells, γδ T cells, and Vδ2 T cells, fractalkine levels were inversely correlated with the percentage of CX3CR1+ Vδ1 T cells in SSc patients (rS = −0.55; p = 0.0337).