As a result of the extracellular ADO accumulation, followed by the involvement of ADO receptors with G protein (A1, A2A, A2B, and A3), the function of immune cells, including NK cells, is suppressed through various mechanisms [112] that tumor can use this mechanism to escape the immune system [113], while the loss of function of ADO production can cause autoimmune disorders (i.e., encephalomyelitis, multiple sclerosis, rheumatoid arthritis, diabetes, and uveitis) [114]. Here, ADO is linked to multiple sclerosis.