IL6 and neoplasm: Lactate represses differentiation and antigen presentation of dendritic cells (DCs).117,277 Previous study discovered that cocultures of melanoma and prostate carcinoma multicellular tumor spheroids (MCTSs) produced low levels of macrophage colony-stimulating factor (MF-CSF) and interleukin-6 (IL-6), while generating significant amounts of lactic acid.