Monoclonal antibody-recognizing tumor-associated antigen of DBA/2 mouse lymphoma L1210 and its sublines.

Tumor-associated antigens of DBA/2 lymphoma L1210 and three immunologic drug-resistant L1210 sublines were studied by monoclonal antibodies produced by fusing non-Ig secreting BALB/c myeloma cells with spleen cell of DBA/2 mice immunized with L1210 subline cells that are syngeneic with respect of DBA/2 mice. After the cell fusion, two stable clones of antibody-producing hybridomas were selected for further analysis of the antibody specificity by complement-dependent cytotoxicity and quantitative absorption tests. These clones produced a cytotoxic antibody(s) of IgG2 class recognizing a TAA(s) that was expressed strongly on cells of the immunizing subline as well as on cells of their L1210 sublines, but weakly on the parental L1210 cells. Control normal syngeneic mouse tissues and tumors of syngeneic and allogeneic origins, including those that carry known murine leukemia virus-associated antigens, showed no significant reaction with the antibody, whereas two DBA/2 tumors (i.e., L5178Y and p388-D1) showed weak reactivity. Since all three L1210 sublines were more immunogenic than the parental L1210 cells in eliciting host's tumor graft rejection and contained more TAA than the parent line, the data suggest that the monoclonal antibody obtained may be defining the TAA that is involved in tumor rejection.