Preference of the early murine immune response for polymorphic determinants on human lymphoid-leukemia cells and the potential use of monoclonal antibodies to these determinants in leukemia-typing panel.

28 monoclonal antibodies (MCAs) which were produced following immunization of mice with human lymphoid leukemia or lymphoma cells were subjected to extensive specificity testing using immunofluorescence and complement-mediated cytotoxicity assays. All except one of the MCAs reacted with lymphocytes from at least one normal donor, but only 36% reacted with at least one subpopulation of lymphocytes from every normal donor tested. 60% of the MCAs detected polymorphic determinants, the frequency of polymorphism ranging from 27 to 91%, 50% of these MCAs reacting with B lymphocytes but not T lymphocytes. The marked heterogeneity observed when testing human lymphoid leukemias with these MCAs could be explained by both polymorphism and heterogeneity in lymphocyte differentiation marker expression. An awareness of the preferential murine immune response to polymorphic determinants on human lymphoid leukemia cells is essential when interpreting unexpected positive or negative results when testing with MCAs. An MCA believed to be detecting a monomorphic determinant may be detecting a high-frequency (supratypic) polymorphic determinant, and a putative leukemia-specific MCA may be detecting a low-frequency polymorphic determinant. Our panel, which includes MCAs which detect polymorphic determinants, appears useful in following the course of leukemia and may be useful for leukemia classification.