Detection of A1A2 and A2AAm1 heterozygotes among human A blood group phenotypes

Light-microscopic examination of ABH and Lewis antigens in human tracheal and epiglottic glands using the avidin-biotin-peroxidase complex technique

The localization of ABH and Lewis antigens was examined in formalin-fixed, paraffin-embedded human tracheal and epiglottic glands using monoclonal anti A, B, H, Lea and Leb antibodies. The mucous cells of the glands showed reactivity with antibodies corresponding to the respective ABO blood groups of the tissue donors. The mucous cells from one blood group A, Le(a-b-) individual showed no reactivity with any antibodies and those from another blood group A, Le(a-b-) individual showed reactivity only with anti A antibody. In individuals from blood group Le(a + b-) of all ABO groups, the mucous cells reacted exclusively with anti Lea. In blood group O, Le(a-b+) individuals, the mucous cells showed intense reaction with anti H and Leb antibodies and weak to moderate reactivity with anti Lea. In Le(a-b+) individuals of A1, B and A1B blood groups, the mucous cells showed strong reactivity with anti A and/or B antibodies, moderate with anti Leb, weak or no activity with anti Lea and absent with anti H. In blood group A2 Le(a-b+) individuals, the mucous cells stained with anti A were weakly stained or completely unstained with anti H antibody, but cells negative with anti A gave strong positive reactions with anti H antibody.

Tumor-associated blood group antigen expressions and immunoglobulins associated with tumors

As outlined in Figures 1 and 2, the biosynthetic pathways for the expression of the A, B and H, and the Lewis determinant carbohydrate sequence structures, as well as sialylated structures, involves both type 1 and type 2 precursor chains (which may be present as glycolipids and N- or O-linked glycoproteins), and many glycosyltransferases. For tumor cells, there appears to be increased expressions of fucosyl- and sialyltransferases yielding such structures as the Le(x), sialyl-Le(a), and many other similar determinants, which are not found on the normal cell progenitor of the tumor. The types of structures expressed on tumor cells is dependent on the particular fucosyl-, sialyl- and other glycosyltransferase genes activated in the transformation and tumor progression events, the availability of the substrates for the glycosyltransferases (both the precursor sequences and the nucleotide-sugar substrates) which is partly dependent on metabolites available to the tumor mass, and on the genotype of the individual regarding particular glycosyltransferases. Both the loss of A, B and/or H blood group antigen expressions of tumor cells and the relative expressions of the Lewis and sialylated-oligosaccharide determinants may be a consequence of the competing biosynthetic pathways and the glycosyltransferases for common substrate sequences, as well as due to the loss of particular glycosyltransferases concomitant with transformation. All of these factors probably account for the variable expressions of the complex of carbohydrate sequence determinants when comparing tumor sections of different individuals as well as the heterogeneity of expression of particular determinants within a single tumor tissue section. As described above, the A, B and/or H determinants, and the precursor sequences, are also expressed to differing extents on epithelial cells depending on the tissue type and cellular location in the tissue. Thus, the differentiation state of the particular epithelial cell also determines the quantity and types of carbohydrate sequences expressed. However, because of the complex nature of the competing biosynthetic pathways for the carbohydrate sequences of glycolipids and glycoproteins, and the relative activations of fucosyl- and sialyltransferases of tumor cells, it would seem that simple deductions as to the state of differentiation of particular tumors with A, B, H and precursor sequence expressions is not warranted.(ABSTRACT TRUNCATED AT 400 WORDS)

A human dispermic chimaera first suspected from analyses of the blood group gene-specified glycosyltransferases

The red cells of a normal male blood donor, K.S., were first grouped as B but he was found to lack anti-A in his serum. Closer investigation revealed that his red cells had very weak A activity, demonstrable only by absorption and elution of anti-A. He is a non-secretor of ABH and a secretor of Lea. Blood group A-, B and H-gene specified glycosyltransferases were detected in his serum. In contrast to the finding of a B antigen of normal strength on his red cells, the B transferase in his serum was only about 30% of the normal level and, despite the very weak A activity of K.S's red cells, the A transferase level was about 50% of that found in the serum of group A individuals with normal strength of A antigen. Moreover, the A transferase on the basis of its pH optimum, Km values for donor and acceptor substrates, activation by divalent cations, isoelectric focusing profile and capacity to convert O to A-active cells, was characterized as the product of an A1 gene. A family study showed that K.S's wife is group A2 and that they have two sons, one group A2 and the other group B. The group B son is assumed to have inherited a B gene from the propositus but the level of B transferase in the son's serum is three times as high as that in his father's serum. The wife of the propositus and his group A2 son have normal A2 transferases in keeping with their A2 red cell status. The A2 son therefore appears to have inherited an A2 gene from his mother but neither the A1 nor the B gene shown to be carried by his father. The distribution of transferase activities in K.S's red cells differs from that in his serum. A level of B transferase within the normal range was found in his red cell membranes but a very low level of A transferase was detected. The discrepancies between the serum transferases and ABO red cell group, together with the pattern of inheritance within the family, led to a suspicion of chimaerism. This was confirmed by the finding of fibroblasts with the female 46XX karyotype in cultures of the propositus' skin. These results suggest that K.S. is a dispermic chimaera with two different cell lines of the genotypes BO and A1O or A1A1. The group A2 son is assumed to have inherited an O gene from his father. It seems probable that K.S.'s bone marrow and reproductive organs are comprised predominantly of the XY cell line which carried the blood group BO genotype whereas his skin and other tissues which contribute the A1 transferase to his plasma, are partly made up of the XX cell line which carries the blood group A1O or A1A1 genotype.

alpha-N-acetyl-D-galactosaminyl- and alpha-D-galactosyltransferase activities in sera of cis AB blood group individuals

Thirteen cis AB persons from five families were examined for serum glycosyltransferase activities associated with the biosynthesis of A and B blood group characters. Their transferases were generally homogeneous within one family, except for A2/cis AB genotypes, whose A enzyme level was similar to the A2 normal sera, but they varied from one family to another. These activities differed quantitatively and qualitatively from A, B and AB normal sera. Studies of A transferase showed variations in the pH-dependent curve, the effect of cofactors and the capacity of conversion of O red cells into A-active cells. Moreover, A and B transferases behaved differently with respect to their relative levels than did AB heterozygous normal sera. The results were discussed and it was suggested that a mutation of a single enzyme transferring both galactose and N-acetyl-galactosamine could explain these properties.