CXCL8 and vitamin D deficiency: Compared with those having normal serum vitamin D levels, participants with vitamin D deficiency and insufficiency had higher circulating concentrations of interleukin (IL) 6 (29 [16–45] pg/ml, 23 [14–40] pg/ml vs 18 [14–32] pg/ml, p = 0.01), and IL-8 (24 [86–655] pg/ml, 207 [81–853] pg/ml vs 98 [67–224], p = 0.03).