A NOVEL MONOCLONAL-ANTIBODY RECOGNIZING HUMAN THYMOCYTES AND B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA CELLS

This paper describes a new murine monoclonal antibody, UN5, raised aga inst human thymocytes. This antibody recognizes a molecule of approxim ately 45 kDa on thymocytes. Flow cytometric analysis reveals a high in tensity of labeling with the majority of thymocytes, whereas only CD20 (+) cells from peripheral whole-blood samples are weakly stained. Peri pheral T cells, granulocytes, platelets and red blood cells do not exp ress this antigen, while monocytes are only weakly labeled by UN5. Fur thermore, the UN5 antibody discriminates between different types of B- cell malignancies, reacting with a subgroup of B-cell chronic lymphocy tic leukemias and hairy cell leukemias, but not with the other kinds o f hematopoietic malignancies tested. Antibody UN5 should prove a usefu l tool for the study of T-cell precursors and for analysis of both nor mal and neoplastic B cells.