A MONOCLONAL-ANTIBODY AGAINST A HUMAN B-LYMPHOBLASTOID CELL-LINE INDUCES TUMOR-REGRESSION IN MICE

We have developed a monoclonal antibody (BAT) to Daudi B lymphoblastoi d cell line membranes. The antibody was selected for its ability to st imulate lymphocyte proliferation. Splenocytes of BALB/c or C57BL mice given i.v. injections of 10 mu g/mouse of BAT exhibited increased prol iferation and cytotoxic activity. A single i.v. administration of BAT monoclonal antibody 2 weeks after B16 melanoma cell inoculation result ed in a striking antitumor effect as manifested by the elimination of lung metastases and prolonged survival of the treated mice. BAT monocl onal antibody was also effective in the regression of tumors in mice b earing 3LL (Lewis lung carcinoma) and MCA-105 (fibrosarcoma). Transfer of 10(7)-10(8) splenocytes from mice that had been given injections o f BAT to B16- or 3LL-inoculated recipients led to a reduction of lung metastases. Splenocytes from B16-inoculated mice that were cured by BA T were more effective than those from mice treated with BAT alone agai nst recipients bearing either B16 or 3LL tumors. The antitumor activit y of BAT is related to its immunostimulatory properties.