Characterization of a monoclonal antibody recognizing a 138 kDa glioblastoma-associated antigen.

A monoclonal antibody (A7) was produced which recognizes an oncofetal antigen expressed on glioblastoma multiforme cells, fetal brain, fetal kidney, but not adult tissues. Radioimmunoprecipitates of Zwittergent 3-14 solubilized glioblastoma cells identified a single band at 138 kDa on 8% polyacrylamide sodium dodecylsulfate gels. Distribution studies of A7 in mice demonstrated a tri-phasic serum clearance of t1/2 alpha = 2.1 h, t1/2 beta = 16.7 h and t1/2 gamma = 151.1 h. Tumor localization studies using the U-87 MG xenograft demonstrated the ability of A7 to localize with a tumor:blood ratio of 1.294 +/- 0.094 as compared with 0.293 +/- 0.051 for control antibody AC. A7 does not damage cell membranes and is not internalized when bound to reactive tumor cells.