A monoclonal surface immunoglobulin (IgM/D-L) with specificity for surface antigen of ox red blood cells in a patient with leukemic lymphosarcoma.

A patient with B-cell leukemic lymphosarcoma, whose lymphocytes had a monoclonal (IgM/D-L) surface immunoglobulin (SmIg) and formed rosettes with ox red blood cells (ORBC), is described. The leukemic cells were documented to have a monoclonal SmIg and cytoplasmic Ig (CIg) and secreted a monoclonal immunoglobulin (MIg) whose antibody activity was directed to the surface antigen of ORBC. Pretreatment of the leukemic cells with anti-mu, anti-delta, or anti-lambda inhibited E(ox) rosette formation specifically. Pretreatment of the leukemic cells with pronase removed the SmIg and abolished E(ox) rosette formation simultaneously, and regeneration of the SmIg was parallel with recovery of the rosette formation. A small amount of serum MIg could be detected by agarose gel electrophoresis and antiidiotypic antibody against the 19 S component of the serum revealed that the monoclonal SmIg, CIg, and serum MIg shared the same idiotope. This case suggests that lymphocytes of some B-cell malignancies may bind to ORBC through SmIg.