Yoshihisa Miyata

Allelic variants of the human MHC class I chain-related B gene (MICB).

Abstract The human major histocompatibility complex (MHC) is located within a 4 megabase segment on chromosome 6p21.3. Recently, a highly divergent MHC class I chain-related gene family, MIC was identified within the class I region. The MICA and MICB genes in this family have unique patterns of tissue expression. The MICA gene is highly polymorphic, with more than 20 alleles identified to date. To elucidate the extent of MICB allelic variations, we sequenced exons 2 (α1), 3 (α2), 4 (α3), and 5 (transmembrane) as well as introns 2 and 4 of this gene in 46 HLA homozygous B-cell lines. We report the identification of eleven alleles based on seven non-synonymous, two synonymous, and four intronic nucleotide variations. Interestingly, one allele has a nonsense mutation resulting in a premature termination codon in the α2 domain. Thus, MICB appears to have fewer alleles than MICA, not unlike the allelic ratio between the HLA-C and -B loci. A preliminary linkage analysis of the MICB alleles with those of the closely located MICA and HLA-B genes revealed no conspicuous linkage disequilibrium between them, implying the presence of a potential recombination hotspot between the MICB and MICA genes.

Changes in En(a-) human red blood cell membranes during in vivo ageing

The human red blood cells with phenotype En(a-) were characterized by the lack of MN antigens. The red blood cells with phenotype En(a-) which were found in a Japanese family were tested to clarify the changes in membrane surfaces of the red blood cells during in vivo ageing. The contents of sialic acid, glucose, mannose, galactose, fucose, N-acetylglucosamine and N-acetylgalactosamine of the red blood cell membranes obtained from the old red blood cells with phenotype En(a-) were significantly lower than those of the young red blood cell membranes. Neither the young nor the old red blood cells with phenotype En(a-) showed the agglutination with Arachis hypogaea (PNA) which was capable of binding to T agglutinogen. It is presumed that En(a-) red blood cells are not exposed to sialidase in vivo. In comparison with the young En(a-) red blood cell membranes, the number and the distribution density of lectin receptor sites on the old ones for Limulus polyphemus (LPA), Canavalia ensiformis (Con A), Triticum vulgaris (WGA) and Bauhinia purpurea (BPA) were significantly lower. It is thought that En(a-) red blood cell ageing is accompanied by elimination of some sialoglycoconjugates which have affinity for LPA, Con A, WGA and BPA, whereas En(a-) red blood cells lack glycophorin A.

The first example of anti-Ula and Ul(a+) red cells found in Japan

negative) phenotypes has been described.2 All previously reported individuals with Gy(a-) red cells have been Caucasians of central European (Romany) ancestry. We detected anti-Gya in the serum of a Japanese blood donor whose red cells were Jc-, Hy-, Gy(a-). The proposita was a 39-yearold female donor who had had two normal pregnancies and no abortions, and who had never been transfused. This is the first example of the rare blood group phenotype Gy(a-) to be found in Japan. Family studies did not reveal any other persons with Hy-, Gy(a-) red cells. The parents of the proposita were first cousins. We tested samples from more than 9350 donors with antiGya but did not detect another Gy(a-) sample. However, five Japanese with Gy(a-) red cells were found in other blood centers (Okayama, Sasebo, Kawasaki, Hokkaido, and Okinawa). One of these persons was a patient suffering from mammary cancer, and the others were blood donors. All persons with Gy(a-) red cells found were women, and each had anti-Gya in the serum. It is probable that these antibodies were stimulated by pregnancy. We thank Dr. G.L. Daniels, MRC Blood Group Unit London, who tested the first blood sample with anti-Gya described above. YASUTO OKUBO, MD NOBUO NAGAO, MT TADAO TOMITA, MT HIDEO YAMAGUCHI, MD Osaka Red Cross Blood Center, 4-43 Morinomiya, 2-chome Jotoku, Osaka 536, Japan JOHN J. MOULDS, MT(ASCP)SBB Gamma Biologicals, Inc., 3700 Mangum Road Houston, TX 77092