CD80 and osteosarcoma: Specifically, CD80 expression on CD62L+ myeloid dendritic cells (OR: 3.41 [95% CI: 1.40 to 8.31], p = 0.007) and the absolute count of CD28−CD4−CD8− T cells (OR: 4.49 [95% CI: 1.29 to 15.62], p = 0.018) were found be positively associated with osteosarcoma in the IVW analysis.