Secretory cell immunoscreening assay--a highly sensitive screening method for secretory cells.

We have developed a rapid and sensitive screening method to detect the secretory product from transformed secretory cells. Polyclonal antibodies against the target secretory protein are first adsorbed onto a nitrocellulose membrane and are then called solid-phase antibodies. Then this membrane is placed on top of target protein-secreting adherent animal cell colonies. After trapping the secreted protein on the membrane, the protein is detected using the highly sensitive enhanced chemiluminescence detection system. Thus, this method is named the secretory cell immunoscreening assay (SCISA). We have screened recombinant BHK-21 cells, which secrete human interleukin-6 (hIL-6) for highly productive clones. With the SCISA method, it is possible to detect less than 100 pg of hIL-6 secreted by a single colony. We are also able to select highly productive colonies rapidly and easily from a large sample population of transformed cell colonies.