The Monoclonal Antimonocyte Antibody My4 Stains B Lymphocytes and Two Distinct Monocyte Subsets in Human Peripheral Blood

Abstract

The monoclonal antibody (MAB) My4 was produced against human myelo-monocytic leukemia cells and stains regular monocytes with high intensity. Employing logarithmic amplification in immunofluorescence flow cytometry an additional low intensity - My4⁺ - and a very low intensity population - My4^{( + )} - can be identified. Light scatter analysis reveals monocyte features for the My4⁺⁺ and for the My4⁺ cells, while the My4^{( + )} cells exhibit characteristics of lymphocytes. The two low intensity (My4⁺ and My4^{( + )}) populations are clearly discernable only after two color immunofluorescence analysis using MABs VEP13 (CD16) and B1 (CD20). The My4⁺ cells coexpress the CD16 antigen and comprise a unique monocyte subset. The My4^{( + )} cells coexpress the B1 antigen, characteristic of B cells. In addition, the My4^{( + )} cells are depleted after treatment of mononuclear cells with the anti-B cell MAB BA-1 plus complement. Finally, leukemic cells from patients with B cell type chronic lymphocytic lemkemia are stained in 18/20 cases. Hence, the MAB My4 identifies regular monocytes and in addition, with lower intensity of staining a new monocyte subset and a subset of B cells in human peripheral blood.