Identification and characterization of a galactosyl peptide mimetic. Implications for use in removing xenoreactive anti-A Gal antibodies.

Gal alpha 1,3 Gal is thought to be the major antigenic epitope present on pig tissues to which XNAs bind. Removal of antibodies directed against that structure may be critical to the success of pig to human xeno-transplantation. As a first step toward the development of ligands capable of removing XNAs, we have used a phage-displayed peptide library to identify a six-amino-acid peptide that binds to the lectin GS-1-B4 (which binds the carbohydrate Gal alpha 1,3 Gal). This peptide blocks the binding of GS-1-B4 to pig aortic endothelial cells. The carbohydrate Gal alpha 1,3 Gal competes with the binding of GS-1-B4 to the peptide, suggesting that they may bind the same site. Using a RBC agglutination assay, we show that this peptide inhibits the agglutination of pig RBCs by heat-inactivated human serum at concentrations similar to that of Gal alpha 1,3 Gal.

[Serum and immunological markers of progression to acquired immunodeficiency syndrome in hemophiliacs]. / Marcadores séricos e inmunológicos de progresión a síndrome de inmunodeficiencia adquirida en hemofílicos.

In a cohort of 30 randomly selected hemophiliacs who were prospectively controlled for four years the predictive value of AIDS development was evaluated for serum markers of HIV infection and for lymphocytic subpopulations in peripheral blood. The patients were evaluated with a mean of 15.79 +/- 5.74 months, and overall antibodies, specific antibodies (anti-ENV and anti-p24), HIV antigen (Ag HIV) and lymphocyte subpopulations were determined. 50% of the hemophiliacs with positive serum Ag HIV (2/4) developed AIDS during the study, whereas this progression was not recorded in any anti-HIV positive, nonantigenic patient. The presence of Ag-HIV was detected at least two years before the diagnosis in these patients, and it was associated with the absence of anti-p24 in one or more determinations. The immune regulation parameters were not significantly different, at the beginning of the study, in the hemophiliacs who developed AIDS and in those who did not. However, the progression to AIDS was associated with a significantly smaller T4/T8 ratio at least one year before the diagnosis. Our results show that the development of AIDS in hemophiliacs is associated both with the presence of Ag-HIV in the serum and a reduction in the T4/T8 ratio, although the detection of the former appears to be earlier than that of the latter in this risk group.

The presence of UDP-N-acetylglucosamine:alpha-3-D-mannoside beta 1,2-N-acetylglucosaminyltransferase I activity in Spodoptera frugiperda cells (IPLB-SF-21AE) and its enhancement as a result of baculovirus infection.

A Golgi preparation from Spodoptera frugiperda (IPLB-SF-21AE) cells was incubated in the presence of the mannosidase II inhibitor, swainsonine, with the oligosaccharide, M(alpha 1,3)[[M(alpha 1,3)[M(alpha 1,6)]M(alpha 1,6)]] M(beta 1,4)Gn(beta 1,4)Gn (M5Gn2), the preferred substrate for the enzyme, UDP-N-acetylglucosamine:alpha-3-D-mannoside beta 1,2-N-acetylglucosaminyltransferase I (Gn-TI). This resulted in formation of the product, Gn(beta 1,2)M(alpha 1,3)[[M(alpha 1,3)[M(alpha 1,6)]M(alpha 1,6)]]- M(beta 1,4) Gn(beta 1,4)Gn (Gn(I)M5Gn2). A significantly increased (> 4-fold) rate of conversion of M5Gn2 to Gn(I)M5Gn2 occurred with insect cell-derived Golgi preparations that had been infected with a recombinant baculovirus for 66 h, a time at which significant amounts of complex-type oligosaccharides were assembled on a heterologous protein, human plasminogen, expressed in this system. Coupled with previous results (Davidson, D.J., Bretthauer, R.K., and Castellino, F.J. (1991) Biochemistry 30, 9811-9815) that demonstrated the occurrence of virally induced activation of a specific M6-mannosidase in IPLB-SF-21AE cells, it is clear that viral infection of lepidopteran insect cells makes available enzymes that provide and utilize the substrate, M5Gn2-protein. This is a key feature in the explanation of the previous original observations made by this laboratory, that lepidopteran insect cells are capable of assembly of complex-type oligosaccharides on glycoproteins.