[Application of the HLA system to forensic medicine--from serology to DNA polymorphism].

HLA antigens are highly polymorphic and therefore considered useful for personal identification in forensic medicine. The HLA system was first applied to forensic medicine for serological typing and is currently being applied to DNA typing. We first applied the HLA system to serological typing for paternity testing. Exclusion of paternity was confirmed in 39 of 93 cases. While serological HLA typing and other testing yielded consistent results in 37 of these 39 cases, exclusion of paternity could be confirmed only by serological HLA typing in 1 case and only by other testing in 1 case. Even in cases where exclusion could not be confirmed, it was possible to increase the probability of paternity. Bloodstains with known HLA types were then subjected to lymphocytotoxic inhibition tests to detect HLA antigens using one of the following methods: a two-stage method using an antibody and a bloodstain extract; a one-stage method where a bloodstain was allowed to react directly with an antiserum; or a washing method where washing was combined with one of the two above methods. Although HLA antigen detection was possible using any of these methods, some antisera yielded false-positive reactions, which limited the range of usable antisera. With the exception of cross-reactions, the washing method eliminated false-positive reactions. Antigens were detectable in bloodstains that were left to stand for up to 42 days. DNA typing based on the HLA system was investigated by determining DR and DQB1 types using the Hot Start PCR-SSP method with various samples of known HLA types and tissue samples collected from unidentified corpses. With bloodstains, DR typing was possible in all 61 cases, while DQB1 typing was possible in 31 of 33 cases. DR typing was possible even when bloodstains had been stored for 10 to 20 years. With saliva stains, typing was possible in all cases by purifying DNA using a Microcon 100 microconcentrator. With hair samples, typing was possible with all hair root samples and about half of hair shaft samples. With mixed stains, the detection of minor components was possible even at a low mixing ratio of 10:1. With cigarette butts, as was the case with saliva stains, typing was possible using purified DNA. Lipstick did not affect the results of DNA typing. Although DNA typing was possible in many cases using tissue samples collected from unidentified corpses, the results were affected by factors such as status of corpse, postmortem interval, postmortem change and tissue type. With some aorta samples, for example, typing was possible up to one year after death. The results of typing were also fairly favorable using bone samples.