Membrane antigens of human cells of the monocyte/macrophage lineage studied with monoclonal antibodies.

Three monoclonal antibodies, FMC17, FMC32, and FMC33 directed against human cells of the monocyte-macrophage lineage are described. The antibodies react strongly with blood monocytes and weakly, if at all, with granulocytes. Lymphoid cells are not stained. In tissue sections macrophages and interdigitating reticulum cells are stained. Lymphoid leukemia cells generally do not react with the antibodies, while myeloid leukemia cells give a variable pattern, with relatively differentiated cells more likely to react than undifferentiated cells. Differences between the 3 antibodies in their reactivity with leukemic cells and tissue macrophages indicate that they are directed against distinct antigens, which may serve as differentiation markers in the monocyte/macrophage lineage.