Prostate cancer cells exhibit different degrees of HLA loss. (a) Section showing a normal level of HLA expression. (b) Section showing partial HLA down regulation: Complete loss of HC10 reactivity is seen in some of the adenocarcinoma glands, while in other adenocarcinoma glands HC10 reactivity is observed. (c, d) Sections with complete HLA down regulation: Expression of HLA is seen in vascular endothelial cells (c and d) and PIN (d), but not in adenocarcinoma cribriform clusters or glands.