p69,71 antigen complex detected by monoclonal antibody Leu 1 in the identification of particular stages of malignant B-cell differentiation.

Lymphomatous cell samples from 86 patients with B-cell neoplasia (34 chronic lymphocytic leukaemia, 8 hairy-cell leukaemia, 5 prolymphocytic leukaemia, 20 immunocytic lymphoma, 9 centrocytic lymphoma, 3 centroblastic/centrocytic lymphoma, 3 lymphoblastic lymphoma, 1 plasma cell leukaemia and 3 plasmacytoma) were studied using the monoclonal antibody Leu 1, detecting a p69,71 antigen complex present on nearly all thymocytes, most (greater than 85%) peripheral T-lymphocytes as well as some malignant B-cells. Furthermore, we compared the reactivity of Leu 1-positive B-cells with those exhibiting conventional surface markers such as mouse-erythrocyte-receptor, FcIgG-receptor, C3b- or C3d-receptor and surface immunoglobulins of the various heavy- and light-chain types. Our results demonstrate a correlation between the expression of p69,71 antigen complex and distinct phenotypes revealed by conventional markers and underline the value of Leu 1 monoclonal antibody in the differential diagnosis of human B-cell neoplasia.