Studies by crossed electroimmunodiffusion on the individuality and sexual orgin of bloodstains.

Crossed electroimmunodiffusion (CEID) was evaluated as a means for individualizing human blood stains by studying variations within and among individuals in 22 serum antigens in ten subjects over a four-month period. The extent of variation within an individual was determined by making CEID runs on blood stains obtained on ten different occasions and measuring the precipitin peak heights produced by each of the 22 antigens. When the range in height of any particular peak was completely different in subject-subject comparisons, the peak was judged to be of value in individualization. By this criterion, each of the ten subjects could be distinguished from all others (65 subject-subject distinctions), but in most cases the distinction had to be based on difference in 5 or less of the 22 antigens. The antigens of value in distinguishing among males were largely different from those of value in distinguishing among females. Overall, the antigens of greatest value in individualization were 8, 9, 10, and 11. Only one of these (10, ceruloplasmin) could be identified as a particular serum proteins.