Surface IgMκ of Prolymphocytic Leukaemia Cells with Antibody Activity to Surface Antigens of Sheep and Guinea-Pig Red Blood Cells

Summary. The immunological findings of a B-cell prolymphocytic leukaemia forming spontaneous rosettes with sheep (SRBC) and guinea-pig red blood cells (GPRBC) are reported. The B-cell lineage was revealed by Ia-like antigen, surface IgMK and lack of cytotoxicity of anti-human T-cell serum. Despite B-cell characteristics, prolymphocytes formed spontaneous rosettes with SRBC. Inhibition procedures demonstrated rosette formation to be the result of antibody activity of surface IGM to SRBC and GPRBC. Pretreatment of prolymphocytes with pronase or antibodies to μ or K-chains inhibited rosette formation. Furthermore, pre-treatment of SRBC with the patient's serum or IgM decreased rosette formation demonstrating circulating antibodies to antigen(s) of SRBC. Antigen(s) on SRBC and GPRBC are not related to Forssman or Paul Bunnel antigen.