CD57 (HNK-1) is an antigen associated with natural killer cells. It is also found in T-cell subsets and B cell subsets. This antibody is similar to HNK-1 and Leu-7. It detects CD 57 antigen (110kD) on the surface of NK cells in germinal centers, and almost 20% of peripheral blood mononuclear cells in adult. It may cross react to myelin-associated glycoprotein of peripheral nerves and prostate surface antigen. This antibody may be useful for the study of NK cell-mediated cytotoxity and functional properties of NK cells and T-cell subsets.