Structural diversity and biological importance of ABO, H, Lewis and secretor histo-blood group carbohydrates

ABSTRACT ABO, H, secretor and Lewis histo-blood system genes control the expression of part of the carbohydrate repertoire present in areas of the body occupied by microorganisms. These carbohydrates, besides having great structural diversity, act as potential receptors for pathogenic and non-pathogenic microorganisms influencing susceptibility and resistance to infection and illness. Despite the knowledge of some structural variability of these carbohydrate antigens and their polymorphic levels of expression in tissue and exocrine secretions, little is known about their biological importance and potential applications in medicine. This review highlights the structural diversity, the biological importance and potential applications of ABO, H, Lewis and secretor histo-blood carbohydrates.

Falta de associação entre o sistema Lewis e obstrução coronariana / Lack of association between the Lewis blood group system and coronary vessel obstruction

Estudos prévios demonstraram associação entre o sistema Lewis e a doença arterial coronariana (DAC) a partir da observação de que o fenótipo eritrocitário Le(a-b-) era prevalente em pacientes e propuseram que esse fenótipo representava um novo marcador de risco para essa doença. Esse estudo teve como objetivo verificar a prevalência desse marcador em pacientes brasileiros com indicação de realizar cineangiocoronariografia. A fenotipagem do sistema Lewis foi realizada pelo método gel centrifugação, e a genotipagem do loco LE foi feita pelo método PCR-RFLP. Cento e oitenta e três pacientes (114 masculinos e 69 femininos, com média de idade igual a 59,1 anos (DP ± 12,37; mediana 60) foram selecionados. Cento e vinte e um (66,1 por cento) pacientes apresentaram obstrução coronariana de qualquer grau, sendo essa característica duas vezes mais elevada no sexo masculino do que no feminino (p=0,07). As freqüências dos fenótipos eritrocitários Lewis foram semelhantes em ambos os grupos de pacientes e o fenótipo Le(a-b-) mostrou-se não estar associado à presença de obstrução coronariana (p=0,36). Elevados índices de discrepância fenótipo-genótipo foram observados entre os pacientes Le(a-b-), com base na genotipagem das mutações T59G (86,7 por cento) e T1067A (90,0 por cento). As freqüências dos alelos T e G (posição 59) e T e A (posição 1067) não mostraram diferenças estatisticamente significantes entre os pacientes com e sem obstrução coronariana (p = 0,52 e p = 0,44, respectivamente). Esses resultados demonstram que o sistema Lewis não está associado à presença de obstrução coronariana e não suportam a proposição de que o fenótipo eritrocitário Le(a-b-) representa um marcador de risco para essa doença na casuística brasileira.

Previous studies have shown an association between the Lewis blood group system and coronary artery disease (CAD) from the observation that the Le(a-b-) red blood cell phenotype was prevalent among these patients and thus proposed this red blood cell phenotype as a new genetic marker for the disease. The aim of this study was to verify the prevalence of this genetic marker among Brazilian patients who had undergone coronary arteriography. Phenotyping of the Lewis system was carried out using gel centrifugation and genotyping of the LE locus was made using PCR-RFLP. One hundred and eighty-three patients, 114 male and 69 female, with an average age of 59.1 years (SD ± 12.37; median 60), were enrolled. One hundred and twenty-one (66.1 percent) patients presented some degree of coronary obstruction, which was two times more frequent in men compared to women (p=0.07). The frequencies of the Lewis red blood cell phenotypes were similar between patients with and without coronary obstruction and the Le(a-b-) was not associated to the presence of coronary obstructions (p=0.36). A high level of discrepancies between phenotype and genotype were observed in Lewis negative patients based on genotyping of the T59G (86.7 percent) and T1067A (90.0 percent) SNPs. The frequencies of T and G alleles (position 59) and T and A alleles (position 1067) were similar among patients with and without coronary obstructions (p = 0.52 and p= 0.44, respectively). These results show that the Lewis system is not associated with the presence of coronary artery obstruction and do not support the proposition that the Le(a-b-) red blood cell phenotype represents a risk marker for this disease among Brazilian patients.