Human B-lymphocyte heteroantigens: direct evidence for specificities not shared by monocytes.

A heterologous anti-human B-lymphocyte serum was raised in the rabbit and rendered specific by extensive absorptions. After absorptions with erythrocytes and thymocytes, the antiserum was cytotoxic for an average of 18·5% of normal peripheral blood lymphocytes. Most chronic lymphatic leukaemia cells and hairy cells' were sensitive to this antiserum but null cells' were not. E-rosette-forming cells were insensitive to the antiserum, while EAC-rosettes and rosettes with mouse erythrocytes were partially or totally inhibited. In ultrastructural characterization studies after immunoperoxydase labelling, it was demonstrated that not only B lymphocytes, but also virtually all monocytes having phagocytized latex particles, were stained. A further absorption with monocytic cells from a patient with subacute myelomonocytic leukaemia was thus performed and the resulting antiserum was then specific for human B lymphocytes only and did not label any latex-phagocytizing monocyte. These results demonstrate that besides antigens common to monocytes, B lymphocytes express specificities characteristic of the B-cell population only, at their surface.