CXCL12 and chronic obstructive pulmonary disease: Some additional chemokines and cytokines showed a significant positive association with female COPD smokers following stratification by gender, including CXCL10 (p = 0.004, r = 0.88), CXCL12 (p = 0.02, r = 0.73), CCL3 (p = 0.002, r = 0.88), interleukin (IL)-12 (p = 0.05, r = 0.67), and IL-13 (p = 0.01, r = 0.81) (Table 2).