Removal of background label in immunocytochemistry with the apolar Lowicryls by using washed protein A-gold-precoupled antibodies in a one-step procedure.

Antiserum mixed with protein A-gold produces aggregates that can be washed by centrifugation and redissociated by ultrasonication. These precoupled antibodies are used for immunocytochemical labeling in a one-step procedure and reveal a very low background on sections of material embedded in polar and apolar Lowicryls. Controls have shown that the background label stems from serum components with only one protein A binding site and is discarded during the wash steps of the precoupling procedure.