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We present the results of AG antigen typings of three Caucasoid population samples: Lebanese, Tunisians, and Finns. AG haplotype frequencies estimated by maximum-likelihood methods are compared with the frequencies observed in 13 world populations previously tested for AG specificities by computing a genetic distance matrix used in a multivariate analysis. A high degree of polymorphism characterizes the three samples, with 10 haplotypes detected in the Lebanese and 11 haplotypes detected in the Tunisians and Finns; high heterozygosity levels are also present in the three populations. The genetic distance analysis shows that the three populations possess a genetic structure intermediate between those observed in sub-Saharan Africans and in Caucasoids from the Near East and India. This tight correspondence between AG differentiation and geography is confirmed by a highly significant correlation coefficient found between genetic and geographic distances computed worldwide, suggesting that an isolation by distance model of evolution applies to the AG system. The Ewens-Watterson test for selective neutrality on all world populations tested for AG specificities also supports the hypothesis that the AG system behaves like a neutral polymorphism. Overall, the AG differentiation pattern appears to be close to the patterns observed for other serological polymorphisms, such as RH, GM, and HLA, whose evolutionary mechanisms are also discussed.

Since 1986 the factor VIII and IX concentrates of the Central Laboratory, Swiss Red Cross Blood Transfusion Service have been virus inactivated with tri-(n-butyl) phosphate and Tween 80. Clinical studies had shown that both preparations were well tolerated and hemostatically effective; no HIV infection was transmitted. However, safety from transmission of non-A/non-B hepatitis could not be shown since the study included no previously untreated patients. In the meantime, a laboratory test has become available which allows retrospective testing for anti-hepatitis C antibodies in frozen sera of the study patients. 5 of the 26 patients, observed during a 2-year follow-up study, had no HCV antibodies before entering the long-term trial. During this trial, each of these 5 patients substituted an average quantity of 40,200 coagulation factor units (7500-69,000) from 45 production lots. None of these 5 patients developed anti-HCV antibodies, nor did any of them show clinical signs of infection with hepatitis. This suggests that virus inactivation using solvent/detergent treatment reduces the risk of transmission of HCV.

Human low density lipoprotein shows a genetic polymorphism, the so-called Ag-system. it consists of 5 pairs of allelic epitopes, x/y, al/d, c/g, t/z, and h/i, which are localized on apolipoprotein B. We have generated a large number of monoclonal antibodies against low density lipoprotein. Two of them, D2E1 and H11G3, recognize epitopes related to this genetic polymorphism. Direct ELISA and ELISA inhibition experiments with different low density lipoproteins of known phenotype showed that D2E1 is directed against the allelic epitope c and H11G3 against d. The two antibodies were used for the characterization of low density lipoprotein in sera from different blood donors and the results compared to those obtained by passive hemagglutination using human allotypic anti-sera. Sera from homo- or heterozygous donors (which display the relevant epitope) could be distinguished from the sera of homozygous donors (which lack the epitope) with the monoclonal antibodies described.