Microcytotoxicity blocking assay for the detection and isolation of soluble astrocytoma association antigen

A blocking microcytotoxicity assay was used to detect soluble astrocytoma-associated antigen. The richest source of soluble antigen was found in spent culture media from an established glioblastoma (GF) tissue culture line. Also assayed were fractions of sonicated membrane antigen from another (GM) glioblastoma and pellets of GF and GM cultured glioblastoma tissue. Blocking by media conditioned by cultured normal human brain, breast cancer, neuroblastoma, meningioma, or 2-year-old astrocytoma cell lines was 41-82% lower. A monomer was isolated that blocked cytotoxicity and migrated in molecular exclusion chromatography with alpha-macroglobulins rather than the beta-2-microglobulins usually associated with histocompatibility antigens.