The CD57 (HI57a) antibody recognizes a 110-115 kDa carbohydrate antigen also called B3GAT1, HNK-1 and Leu7. CD57 antigen is e, Xenopus/Amphibian,pressed on 12-20% of normal peripheral blood lymphocytes including subsets of NK cells and CD8+ Ts/Tc. CD57 e, Xenopus/Amphibian,pression increases with age in peripheral blood lymphocytes to 25-40% in patients over 80 year-old. CD57 is not e, Xenopus/Amphibian,pressed by cord blood lymphocytes, B lymphocytes,Mouse,onocytes, granulocytes,Porcinelatelets and erythrocytes. CD57+ cell population increases in pathologies characterized by an imbalance of CD4/CD8 lymphocytes, e.g. AIDS, autoimmune diseases, allograft transplants, and viral infections. The CD57 molecule is shared by normal neural and striated muscle and their neoplastic counterparts including neurofibromas, neurofibrosarcomas and malignant melanomas. CD57 is also present on normal and neoplastic prostatic epithelia, where it represents a prognostic factor showing a positive correlation between the number of CD57+ cells and an increased survival of the neoplastic patients.