The purpose of this study was to ascertain how various growth parameters may influence the labeling of SK-MG-1, a human glioma cell line, by BT32/A6, a human immunoglobulin M monoclonal antibody (MAb). By growing SK-MG-1 cells at different culture split ratios, significant trends in cell growth rate, culture viability, and cell cycle state were produced. Labeling of SK-MG-1 cells by BT32/A6, however, was shown to be unaffected by culture split ratio (p > 0.05) and is therefore independent of cell growth rate, culture viability, and cell cycle state. Using flow cytometry and fluorescence-activated cell sorting, BT32/A6 was shown to label a cell surface antigen on viable, clonogenic cells of SK-MG-1. Approximately 100% of SK-MG-1 cells were shown by flow cytometry to express the BT32/A6 antigen. The recognition of a glioma-associated, cell cycle-independent surface antigen by MAb BT32/A6 makes it a promising candidate for further studies aimed at elucidating its usefulness as an adjunct in the treatment of human malignant gliomas.