Activation of human lymphocytes by a monoclonal antibody to B lymphoblastoid cells; molecular mass and distribution of binding protein.

A novel monoclonal antibody (BAT) to the B-lymphoblastoid cell line activates murine lymphocytes and exhibits a striking antitumor activity in mice. In order to evaluate the potential use of this antibody against human cancer, we have investigated its immuno-stimulatory properties on human peripheral blood lymphocytes (PBL). Our findings demonstrate that BAT mAb induces proliferation and cytotoxicity in human PBL against natural-killer-cell-sensitive and natural-killer-cell-resistant tumor cell lines. Interleukin-2 at a low concentration synergizes with BAT mAb in eliciting these effects. BAT mAb binds to human peripheral T cells as revealed by a double-labelling technique using anti-CD3 and BAT mAb. The molecular mass of the antigen recognized by BAT mAb was 48-50 kDa under reducing and non-reducing conditions. This study provides a basis for future experiments to evaluate the use of BAT mAb in the immunotherapy of cancer.