The application of immunoblotting to the phenotyping of group-specific component

A sensitive immunoblotting method for the routine detection of group-specific component (GC) from fresh serum, and from control and casework bloodstains has been developed. GC phenotypes were separated in a thin layer polyacrylamide gel by isoelectric focusing, transferred to nitrocellulose by a rapid capillary blotting procedure, and detected using a double antibody enzyme immunoassay. This method is capable of phenotyping 8 ng of GC extracted from bloodstains, a four-fold increase in sensitivity when compared to immunofixation and silverstaining. A total of 2424 casework bloodstains have been analysed and GC phenotypes identified in 78% of samples. The method is suitable for use in routine laboratories and is more sensitive than other methods for GC phenotyping of casework bloodstains.