Calla

Abstract: Previous studies by Greaves1 and others2–6 have demonstrated the existence of an antigen associated with cells from many patients with acute lymphoblastic leukaemia (ALL) and some patients with chronic myelocytic leukaemia (CML) in blast crisis. Antisera to this common ALL antigen (CALLA) have been produced in rabbits and require extensive absorption which limits both the titre and quantity of antisera that can be generated and may result in variable specificity in different laboratories. The method for generation of specific antibody by somatic cell hybridisation introduced by Kohler and Milstein7 has been successfully used to produce monoclonal antibodies against various normal human cell-surface proteins, including β2 microglobulin8, histocompatibility antigens9, thymocyte and peripheral T-cell antigens10–12 and Ia-like antigens13. The present report describes the generation and characterisation of a monoclonal antibody specific for a common ALL antigen (CALLA) previously identified by conventional heteroantisera.

Abstract: The common acute lymphoblastic leukemia antigen (CALLA), as defined by J-5 murine monoclonal antibodies, was detected on renal tubular and glomerular cells from fetal and adult donors by an indirect immunoperoxidase technique. CALLA could also be detected on epithelial cells of the fetal small intestine and on myoepithelial cells of adult breast but not on myoepithelial cells of the salivary gland. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of immunoprecipitated 125I-labeled membrane antigens from dissociated renal cells demonstrated that the antigen migrated as a 90,000 mol wt antigen rather than the 98,000-100,000 mol wt antigen noted on CALLA-positive tissue culture cell lines. The data suggest that the determinant defined by the J-5 monoclonal antibody is neither a lymphoid cell-specific differentiation antigen nor a leukemia-specific antigen.