Among those linked to a reduced risk of osteoporosis were increased percentages of transitional B cells, higher proportions of CD11c+ CD62L− monocytes, elevated BAFF-R expression in IgD− CD38+ B cells, increased CD25 expression in activated CD4+ regulatory T cells, and higher counts of HLA-DR+ natural killer (NK) cells. This evidence concerns the gene CD4 and osteoporosis.