Recently developed
monoclonal antibodies DLC-48 and LN-1 have been shown to be effective
reagents for
complement-mediated cell lysis of human B-cells. The authors have initially found that these
reagents are useful in elimination of
malignant lymphomas cells from human bone marrow for autologous
bone marrow transplantation. In the current study, the authors have further characterized the reactivity of these
antibodies in B-cell
neoplasia and have analyzed the heterogeneity of antigenic expression among benign and neoplastic lymphoid cells for B-cell
monoclonal antibodies. With the use of quantitative flow cytometric techniques to assess heterogeneity of
antigen expression, the findings indicate that phenotypic heterogeneity within
neoplasms from individual patients exists for a number of B-cell-related
monoclonal antibodies, including B1, common acute lymphocyte
leukemia antigen (CALLA), Ia,
Ba-1, DLC-48, and LN-1. Within a given histologic class of lymphoid
neoplasia, phenotypic heterogeneity was found to be a property of some individual cases and not others for all B-cell
monoclonal antibodies examined. This heterogeneity was not consistently expressed in patients with similar
tumors, nor was it a consistent property of a given
antigen. Using cell lines derived from large cell
lymphomas, the authors were able to find phenotypic heterogeneity within neoplastic cell lines that can be used to develop models for dealing with phenotypic heterogeneity in the context of
complement-mediated cell lysis. They also established that for DLC-48 and LN-1, the heterogeneity was not related to the phase of the cell cycle of the proliferating cells. The results suggest that single
monoclonal antibody treatment for bone marrow depletion of neoplastic cell may be insufficient to overcome phenotypic heterogeneity of B-cell
neoplasms.