Park et al. (2000) isolated peripheral blood monocytes from individuals (range 26–68 years old, mean 45 years old) with Down syndrome and age-matched controls and stimulated the cells with LPS. They found no difference in TNFα, IL-6, or IL-8. In contrast to Singh (1994) and Lombardi et al. (1999), they found that monocytes from Down’s syndrome individuals produced 30% less IL-1β than the aged match controls. This evidence concerns the gene CXCL8 and Down syndrome.