An 'indirect" cell separation technique was developed using protein A, in which each specific antiserum was first reacted with the cells to be processed. Separation was then achieved on antibody/protein A immunoadsorbent surfaces, where the final antibody coupled to the protein A was one which was directed against the specific antisera previously reacted with the cells. Only small volumes of specific antisera were required to effect separation either on a small or large scale with excellent specificity, cell viability and total cell recoveries. Theoretically, the technique would function with any Ig class of specific antisera from any species and would not be restricted to mammalian protein A binding IgG specific antisera, allowing considerable expansion in the number of antisera able to be utilized.