The two antibody specificities within human anti-blood group B antibodies

Induction of immune tolerance to a transplantation carbohydrate antigen by gene therapy with autologous lymphocytes transduced with adenovirus containing the corresponding glycosyltransferase gene

Induction of tolerance to transplantation carbohydrate antigens is of clinical significance in recipients of ABO-incompatible allografts, or of xenografts. The experimental animal model used for studying such tolerance was that of alpha1,3galactosyltransferase (alpha1,3GT) knockout (KO) mice, which lacks the alpha-gal epitope (Galalpha1-3Galbeta1-4GlcNAc-R) and which can produce the anti-Gal antibody against it. In contrast, wild-type (WT) mice synthesize the alpha-gal epitope and are immunotolerant to it. KO lymphocytes transduced in vitro with adenovirus containing the alpha1,3GT gene (AdalphaGT) express alpha-gal epitopes. Administration of such lymphocytes into KO mice resulted in tolerization of naïve and memory anti-Gal B cells. Mice tolerized by AdalphaGT transduced lymphocytes failed to produce anti-Gal following immunizations with pig kidney membranes (PKM) expressing multiple alpha-gal epitopes. This tolerance was perpetuated by transplanted syngeneic WT mouse hearts expressing alpha-gal epitopes. Transplanted WT hearts survived in the tolerized KO mice for at least 100 days, despite repeated PKM immunizations. Control mice receiving lymphocytes transduced with adenovirus lacking the alpha1,3GT gene were not tolerized, but produced anti-Gal and rejected transplanted WT hearts. This study suggests that autologous lymphocytes transduced with adenovirus containing A or B transferase genes may induce a similar tolerance to blood group antigens in humans.

Association of malaria with inactivation of alpha1,3-galactosyl transferase in catarrhines

Present-day catarrhines (old world monkeys and hominoids) lack Gal alpha1-3 Gal beta1-4 GlcNAc-R structures (alpha-galactosyl epitopes) and produce the corresponding anti-galactosyl antibodies (anti-gal), while platyrrhines (new world monkeys) and non-primate mammals possess alpha-galactosyl epitopes and lack anti-gal. Anti-gal is shown to inhibit Plasmodium falciparum growth in culture in a concentration dependent manner. probably by binding to alpha-galactosyl epitopes on merozoite surface molecules and causing complement mediated damage. A P. falciparum-like malaria parasite may therefore have selected for the inactivation of an alpha 1-3 galactosyl transferase in catarrhines. The implications of the results for the development of clinical immunity to falciparum malaria are briefly discussed.

Antibodies against terminal galactosyl alpha(1-3) galactose epitopes in patients with idiopathic myelofibrosis

Sera from patients with myelofibrosis were analysed for circulating antibodies against an antigenic determinant characterized by two molecules of galactose in alpha 1-3 linkage (anti-Gal antibodies). 50% of patients were found to have values above the 90th percentile of the values of control sera chosen as a cut-off. The median level of the antibodies was significantly higher than the value detected in normal controls, but no difference could be found between patients with idiopathic myelofibrosis and those with myelofibrosis associated to a chronic myeloproliferative disorder. Anti-Gal antibodies were found to correlate with disease activity and with platelet count whereas no correlation was detected with other haematological parameters. Furthermore, for evaluation of disease activity, determination of serum anti-Gal antibodies was a sensitive and specific parameter. We conclude that humoral immunity against Gal alpha 1-3Gal may provide a sensitive tool to detect disease activity in patients with idiopathic myelofibrosis and may be important for understanding its pathogenesis.

Immunological recognition of larval Taenia crassiceps glycolipids by sera from parasite-infected mice

The isolation and purification of a neutral glycolipid fraction from Taenia crassiceps metacestodes (KBS strain), harvested from both male and female NMRI mice at 70-80 days following intraperitoneal infection, revealed 24 thin-layer chromatography-designated glycolipid bands. The glycolipids were defined as ceramide mono- (n = 3), di- (n = 3), tri- (n = 4), tetra- (n = 5), and greater than tetrasaccharides (n = 9) according to their running properties as defined by thin-layer chromatography against standards of known structure. The defined glycolipids were tested for immunoreactivity with sera from noninfected and T. crassiceps-infected NMRI mice (intraperitoneal injection or implantation of 15 larvae/animal) using the enzyme-linked immunosorbent assay (ELISA) until day 33 p.i. (IgM and IgG reaction) and high-performance thin-layer chromatography (HPTLC) combined with immunostaining (IgG reaction) until day 7 p.i. ELISA-determined IgM and IgG titres were significantly elevated from day 5 p.i. Immunostaining revealed early reactivity for certain ceramide tetra- and greater than tetrasaccharides (n = 6) on day 3 p.i. From day 5 p.i. onwards, nearly all glycolipids, including ceramide mono- and disaccharides, were recognized by the sera from metacestode-challenged mice. On day 7 p.i., a total of 22 bands were serologically active; of these, a considerable number (n = 10) showed increased staining intensity. Remarkably, in many cases (10 of 20), 3 glycolipids (tetra- and greater than tetrasaccharides) were weakly recognized by mouse sera taken before infection.

Abnormal expression of alpha-galactosyl epitopes in man. A trigger for autoimmune processes?

1% of circulating IgG in man is anti-Gal antibody, which interacts specifically with the carbohydrate structure Gal alpha 1----3Gal beta 1----4GlcNAc-R on mammalian glycoconjugates (described throughout as the alpha-galactosyl epitope). This epitope is abundant on cell surface glycoconjugates of non-primate mammals, prosimians, and New World monkeys. It is not found on cells of Old World monkeys, apes, and man because of diminished alpha 1----3 galactosyltransferase enzyme activity. However, the alpha 1----3 galactosyltransferase gene seems to be present within the human genome. A mechanism that increases alpha 1----3 galactosyltransferase activity in human cells could trigger an autoimmune process mediated by anti-Gal binding to the newly synthesised alpha-galactosyl epitopes.