SENSITIVE ALKALINE-PHOSPHATASE LINKED SECONDARY ANTIBODY SYSTEM FOR DETECTION OF GROUP-SPECIFIC COMPONENT AFTER ISOELECTRIC-FOCUSING ON 250 MU-M THICK REUSABLE IMMOBILIZED PH-GRADIENTS

A sensitive secondary antibody system was developed for detection of small amounts of group specific component (Gc). For the first antibody step after focusing, a comparison between immunofixation on cellulose acetate membranes and capillary blotting on nitrocellulose was made. The sensitivity of the first is much better than that of the latter. The method allowed the detection of about 150 picograms of Gc in 1:12800 diluted serum samples. Even in six-year-old badly soluble bloodstains kept at room temperature, Gc could be phenotyped. The 250 .mu.m thick immobilized pH-gradient gels for focusing of Gc can be used repeatedly after washing and drying to the initial weight without destroying the pH gradient.