SHIGA-LIKE TOXIN PURGES HUMAN LYMPHOMA FROM BONE-MARROW OF SEVERE COMBINED IMMUNODEFICIENT MICE

Shiga-like toxin-1 (SLT-1) is a bacterial toxin that kills cells by in hibiting protein synthesis. SLT-1 is composed of one cytotoxic A-subun it and five B-subunits that bind to CD77, a cell-surface glycolipid. I n the human hematopoietic system, CD77 expression is restricted to a s ubset of activated B cells and derived cancers. Here we report that SL T-1 treatment of murine bone marrow ex vivo effectively cures severe c ombined immunodeficient mice of a human B-cell lymphoma xenograft whil e sparing normal hematopoietic precursor cells, Flow cytometry results using fluorescein isothiocyanate-labeled SLT-1 B-subunit show the hig h prevalence of expression of SLT-1 receptors (CD77) in human non-Hodg kin's lymphomas, especially follicular lymphomas. These results sugges t the use of SLT-1 for the purging of human bone marrow before autolog ous bone marrow transplant in the case of CD77(+) B-cell lymphomas as just one of many possible uses. (C) 1996 by The American Society of He matology.