Autologous bone marrow transplantation for leukemia: monoclonal antibody-mediated purging of multidrug-resistant leukemia.

Nine drug-resistant variants of human leukemic/lymphoma cell lines were evaluated for the expression of antigens which are commonly targeted in antibody-dependent purging protocols used for autologous bone marrow transplantation. Flow cytometry revealed that most drug-resistant variants differ in antigen expression from parental lines. Both epipodophyllotoxin-selected T-ALL variants tested expressed lower levels of CD5 than parental counterparts. In contrast, other antigens (CD7, CD3, CD4, CD8, CD38, CD9, CD10, CD24, CD19, CD20) were not consistently altered in drug-resistant variants. Drug-resistant cells were lysed as effectively as drug-sensitive cells by murine antibody and baby rabbit complement, but only when particular monoclonal antibodies or cocktails of monoclonal antibodies were utilized. Two of the nine drug-resistant variants proved to be more resistant than parental cells to antibody-dependent cell-mediated cytolysis (ADCC).