Expression of ABH and X (Lex) antigens in various cells.

Using a panel of reagents specific to the various subtypes of ABH antigens, it could be demonstrated that platelets carry ABH type 2 monofucosylated determinants on intrinsic glycoproteins. The presence of these antigens is controlled by the H gene and correlates with the presence of alpha-2-L-fucosyltransferase and the absence of alpha-3-L-fucosyltransferase. In contrast, intrinsic ABH antigens were not found on mononuclear cells, correlating with the absence of alpha-2-L-fucosyltransferase on these cells. However, after transformation with the Epstein-Barr virus and stimulation with 12-O-tetradecanoylphorbol-13-O-acetate (TPA), B lymphocytes were found to express the H antigen under control of the H gene and not the Se gene. The lymphoblastoid cell lines also expressed the X and sialylated X antigens which are normally markers of the myeloid lineage. These antigens are also normally found in epithelial cells of the digestive tract, kidney proximal convoluted tubules and hepatocytes. The alpha-3-L-fucosyltransferase responsible for the synthesis of this antigen is present in the serum but we report the existence of two individuals, a mother and her daughter, who lack more than 90% of this serum enzyme. The young girl suffers from a congenital kidney anomaly: oligomeganephronic hypoplasia. Her kidney tubules are devoid of X antigen. However, she and her mother have the X antigen on their granulocytes and its sialylated form on their monocytes. It therefore appears that there are distinct genetic controls for the expression of antigen X in different body compartments. This would be quite similar to the H and Se gene controls in tissues of distinct embryological origins.

Expression of ABH and X (Lex) antigens on platelets and lymphocytes.

We used a panel of reagents, polyclonal and monoclonal antibodies, and lectins to define the expression of the ABH- and Lewis-related specificities on platelets and lymphocytes. We also determined the expression of the alpha 2- and alpha 3-L-fucosyltransferases necessary for their biosynthesis. The antigens that could be detected by immunofluorescence and Western blot analysis were based on type 2 monofucosylated structures. Antibodies directed toward types 1, 3, and 4 ABH-, X- and Lewis-related antigenic determinants were always negative because the small amounts of ABH and Lewis antigens adsorbed from the serum could not be detected by these techniques. The presence of the type 2 ABH antigens on intrinsic glycoproteins was controlled by the H gene. This correlates with the presence of alpha 2-L-fucosyltransferase and the absence of alpha 3-L-fucosyltransferase on platelets. In contrast, ABH antigens were not detected by immunofluorescence on normal peripheral lymphocytes. These cells thus have only the small amounts of antigens adsorbed from the serum, these being under control of the secretor and Lewis genes. This correlates with the absence of alpha 2-L-fucosyltransferase on lymphocytes. When lymphocytes were transformed in vitro by the Epstein-Barr virus (EBV), however, they strongly expressed the X and sialylated X antigens, which are specific markers of normal granulocytes and monocytes, respectively. Treatment of EBV-transformed lymphoblastoid cell lines with 12-O-tetradecanoylphorbol-13-O-acetate significantly decreased the expression of X and sialylated X antigens along with that of surface immunoglobulins, whereas it induced a significant expression of the H antigen under control of the H gene.

Failure of expression of alpha-3-L-fucosyltransferase in human serum is coincident with the absence of the X (or Le(x)) antigen in the kidney but not on leucocytes.

The X antigen, beta Gal(1----4)[alpha Fuc(1----3)]beta GlcNAc-R, is mostly found in epithelial cells of the digestive tract, proximal convoluted tubules of the kidney, and granulocytes. The alpha-3-L-fucosyltransferase responsible for synthesis of this antigen is normally present in the serum, but we found 2 individuals, a mother and her daughter, who lack more than 90% of the serum fucosyltransferase. They are of African origin and are both Le(a-b-). The young girl suffers from a congenital kidney anomaly: oligomeganephronic hypoplasia. Her kidney tubules are devoid of X antigen. However, her mother and herself normally possess the X antigen on granulocytes and its sialylated form on monocytes. Anephric patients showed reduced serum alpha-3-L-fucosyltransferase activity, suggesting that the kidney contributes to an important fraction of serum enzymic activity. It, therefore, appears that there are distinct genetic controls governing expression of the X antigen in different body compartments. Possibly, different alpha-3-L-fucosyltransferases could be at work in kidney and leucocytes.

Discordance between red cell and saliva Lewis phenotypes in patients with hydatid cysts.

Patients with hydatid cysts and controls of the same Tunisian area were typed for ABO, Lewis and secretor phenotypes. A high incidence of red cell Le(a-b-) phenotype (34-37%) was found among hydatid cyst patients as compared to normal controls (13-16%). However, a large proportion of the patients with Le(a-b-) red cell phenotype had discordant red cell and saliva Lewis phenotypes since they secreted Lea and/or Leb antigens in saliva. In addition, 1 patient with Le(a+b-) red cell phenotype secreted Leb antigen in saliva. The remaining patients and all the controls had concordant red cell and saliva Lewis phenotypes. The discordant results between the phenotypes obtained in serum and saliva of hydatid cyst patients are probably the consequence of a decrease in the concentration of the circulating Lewis glycosphingolipids, secondary to the disease.