When patients were segregated in two groups defined by the median percentage of CX3CR1 expressing NK cells (87.63%), a higher frequency of pulmonary fibrosis identified by Chest High Resolution Computed Tomography (p = 0.0289) and anti-topoisomerase 1 antibodies (p = 0.0483) was observed in patients with the higher percentages of CX3CR1+ NK cells. The gene discussed is CX3CR1; the disease is pulmonary fibrosis.