Action of alpha-galactosidase from Clostridium sporogenes and coffee beans on blood group B antigen of erythrocytes. The effect on the viability of erythrocytes in circulation

Enzymatic Conversion of RBCs by α-N-Acetylgalactosaminidase from Spirosoma linguale

Spirosoma linguale is a free-living nonpathogenic organism. Like many other bacteria, S. linguale produces a cell-associated α-N-acetylgalactosaminidase. This work was undertaken to elucidate the nature of this activity. The recombinant enzyme was produced, purified, and examined for biochemical attributes. The purified enzyme was ~50 kDa active as a homodimer in solution. It catalyzed hydrolysis of α-N-acetylgalactosamine at pH 7. Calculated K_M was 1.1 mM with k_cat of 173 s⁻¹. The described enzyme belongs to the GH109 family.

Modulating the red cell membrane to produce universal/stealth donor red cells suitable for transfusion

Two approaches have been used to produce universal group O donor red blood cells (RBCs) from groups A, B, and AB RBCs. The first involves cleavage of the terminal immunodominant sugars from carbohydrate chains on the RBC membrane, using specific enzymes, to produce so-called enzyme-converted group O (ECO) RBCs. ECO RBCs have been produced from whole units of B RBCs and transfused successfully to humans. Group A RBCs (especially A(1) RBCs) have been more difficult. New sources of enzymes have produced ECO RBCs from A(1) and A(2) RBCs that do not react with powerful monoclonal anti-A. Unfortunately, there are still problems encountered with polyclonal human antibodies (i.e. cross-matching). The second approach interferes with an antibody reaching its specific antigen on the RBC membrane by bonding polyethylene glycol (PEG) to the RBC. PEG will attract water molecules, yielding a combination that may block most RBC antigens, including A and B antigens. Initial excitement generated by preliminary reports of the possibility of producing 'stealth' PEG-RBCs were tempered by the findings of in vitro serological problems and possible reduced in vivo RBC survival. Many of these problems were solved, but recent findings that PEG is immunogenic in animals and humans, and that PEG antibodies can shorten the survival of PEG-RBCs (in rabbits) and pegylated proteins (e.g. PEG-asparaginase) in humans, are disturbing, suggesting that 'stealth' RBCs may never become a reality.

Blood group B degrading activity of Ruminococcus gnavus alpha-galactosidase

Ruminococcus gnavus is a Gram positive, nonspore-forming obligate anaerobe normally found in the human alimentary tract. In culture, this organism constitutively produces a 1-3 alpha-galactosidase. We fractionated and characterized this enzyme demonstrating hydrolysis of the B epitope on erythrocyte membranes and seroconversion to H epitope (blood type O). Since the enzyme yield was low, cell suspension studies could not be performed. Instead, hydrolysis of the B membrane epitope was studied with an ELISA. A highly purified enzyme product was analyzed for characteristics such as pH, ionic strength, and temperature optimum. Activity in red cell preservative solutions and in the presence of type B plasma was also demonstrated. Ruminococcus gnavus a 1-3 alpha-galactosidase has potential application in the enzymatic conversion of type B to O packed red blood cell units.

Transfusion to blood group A and O patients of group B RBCs that have been enzymatically converted to group O

BACKGROUND

The transfusion of ABO-incompatible RBCs is the leading cause of fatal transfusion reactions. Group O RBCs, lacking terminal immunodominant A and B sugars to which humans are immunized, are safe for transfusion to persons of any ABO blood group. With the use of a recombinant alpha-galactosidase to remove terminal galactose from group B RBCs, the safety and efficacy of enzyme-converted group-B-to-group-O (ECO) RBC components were studied in transfusion-dependent patients.

STUDY DESIGN AND METHODS

Twenty-four patients (blood groups A and O) were randomly assigned to receive transfusion(s) of either ECO or control group O RBCs. If a second transfusion was given, the other blood component was administered.

RESULTS

Twenty-one patients were given ECO RBCs; 18 also underwent control transfusions. One patient received only a small aliquot for RBC survival studies, instead of a full-unit transfusion, because his serum was incompatible with ECO RBCs. No adverse events occurred. Both ECO and control transfusions resulted in appropriate Hb increments and comparable (51)Cr-labeled RBC survival studies. One patient developed a transient, weak-positive DAT, without hemolysis. Two weeks after transfusion, 5 of 19 evaluable ECO RBC recipients had increases in anti-B titers.

CONCLUSION

ECO RBCs were comparable to group O cells for safety and efficacy in this study. The clinical significance of the increase in anti-B and of occasional serologic incompatibilities with ECO RBCs is unclear. If strategies can be developed to remove A epitopes, enzymatic conversion could be used to create a universal (group O) donor blood supply.

Making Landsteiner's discovery superfluous: safety and economic implications of a universal group O red blood cell supply

The risks of ABO-mediated acute immune hemolytic transfusion reactions continue to bedevil modern transfusion services. Of particular concern, the incidence of transfusion fatalities has not changed over time, in stark comparison to the fall in risks of infectious diseases. This article reviews the approaches employed to combat aspects of ABO transfusion errors. The advantages of a universal group O donor pool are considered, and some innovative approaches for achieving this goal, including enzymatic modification of the red cell membrane, the epitope masking through the use of polyethylene glycol, are described. The impact of a group O blood supply on transfusion practices, and on costs to healthcare system, are considered.

Deantigenation of human type B erythrocytes with Glycine max alpha-D-galactosidase

Conversion of erythrocyte membrane B antigen to H antigen produces blood type O which is universally transfusable. If efficient large-scale production of enzymatically converted red blood cells is to be achieved, then optimal conditions for deantigenation must be determined. Cell suspension assays were used to study the blood group B activity of Glycine max (soybean) alpha-D-galactosidase on native human erythrocytes. The enzyme readily hydrolyzed the terminal alpha-D-galactosyl residue of the B antigen, converting it to H antigen. Optimal conditions for the enzymatic conversion of red cells with the Glycine enzyme are described. Normal cell morphology and function were maintained under optimal conditions.

The conversion of group B red blood cells into group O by an alpha-D-galactosidase from taro (Colocasia esculenta)

An alpha-D-galactosidase (EC 3.2.1.21), capable of converting group B into group O red cells, was isolated from the stem portion of taro. It was purified about 3000 fold by gel filtration and ion-exchange chromatography. The blood group-converting activity was demonstrated by hemolysis and hemagglutination studies. This activity is comparable to that of alpha-D-galactosidase isolated from coffee beans. Taro alpha-D-galactosidase also hydrolyzes (1----4)- and (1----6)-linked alpha-D-galactopyranosyl groups from D-galactose-containing glycoconjugates. Taro alpha-D-galactosidase has a low Km value (0.28mM), a low molecular weight (40,000), and a neutral optimal pH (6.0). At a final enzyme concentration of 30 units/mL in the incubation mixture, the conversion of group B into group O activity was completed within two hours, without apparent changes in the shape of the red cells.

Structure and properties of a Cephalosporium acremonium alpha-galactosidase

The amino acid and sugar composition of the enzyme protein, the effect of urea, sodium dodecyl sulphate and Concanavalin A on the purified alpha-galactosidase (EC 3.2.1.22) from the mold Cephalosporium acremonium has been studied. The results obtained by gas liquid chromatography indicated the presence of N-acetylglucosamine, mannose, galactose and N-acetylneuramic acid in the molar proportions 2:7:3:11. The presence of two types of Asn-linked oligosaccharide structures in the enzyme molecule is assumed. The alpha-galactosidase liberates alpha(1-3), alpha(1-4) and alpha(1-6)-linked D-galactose units from various synthetic and natural substrates which have been tested. The effects of pH, substrate concentration and temperature on the catalytic activity of the enzyme are described. The purified alpha-galactosidase also exhibited a lectin activity with an affinity towards glucose, and to some extent mannose.

Effects of alpha-galactosidase digestion on lectin staining in human pancreas

Effects of alpha-galactosidase (from green coffee beans) digestion on lectin staining were examined in formalin-fixed, paraffin-embedded human pancreatic tissues from individuals of blood-group B and AB. Digestion with the enzyme resulted in almost complete loss of Griffonia simplicifolia agglutinin I-B4 (GSAI-B4) staining in the acinar cells with concomitant appearance of Ulex europaeus agglutinin-I(UEA-I) staining in the corresponding cells. In addition, reactivity with soybean agglutinin(SBA) was also imparted by the enzyme digestion in GSAI-B4 positive acinar cells. beta-Galactosidase digestion following alpha-galactosidase digestion neither reduced the reactivity with SBA nor induced the reactivity with Griffonia simplicifolia agglutinin-II(GSA-II) in GSAI-B4 positive cells, while in UEA-I positive cells, both reduction of SBA reactivity and appearance of GSA-II reactivity occurred after simple beta-galactosidase digestion as well as sequential digestion with alpha- and beta-galactosidase. However, when alpha-L-fucosidase digestion procedure was inserted between alpha- and beta-galactosidase digestion, UEA-I staining imparted by alpha-galactosidase digestion was markedly decreased in intensity and GSA-II reactivity was appeared in GSAI-B4 positive acinar cells. Furthermore, after sequential digestion with alpha-galactosidase and fucosidase, reactivity with peanut agglutinin(PNA) was revealed in GSAI-B4 positive acinar cells as well as UEA-I positive cells in secretors. In non-secretors, strong PNA staining was usually observed in the acinar cells throughout the glands without enzyme digestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of 75Se-labeled methionine to study the sequestration of senescent red blood cells

Labeling red blood cells with Na251CrO4 enabled us to study certain aspects of red cell survival and sequestration from the circulation. As a random labeling procedure, however, the 51Cr method has certain limitations. Therefore, we developed a cohort labeling method using 75Se-methionine as a two-rat procedure. This gives us a clear pulse-labeled population of rat red cells to study the dynamics of sequestration. With this labeling procedure, it was possible to demonstrate that 1) there is an increase in the density of red cells with age, 2) a significant sequestration of red cells from the circulation is apparent at the end of 48 days and essentially is complete at the end of 60 days, 3) there is a corresponding uptake of senescent red cells in the spleen, which peaks at 55 days, and 4) the 60-day end point is sharper and is more definitive when the "specific activity" (cpm per red blood cell) of the labeled red cells in the spleen is compared to that of the red cells still in the circulation. Asialo red cells, obtained by removal of sialic acid with sialidase, frequently have been used as a model for the study of sequestration of senescent red cells. With the technique herein described, it was possible to show that while asialo red cells will inhibit the uptake of labeled asialo red cells, they have no effect on the sequestration of senescent red cells. Presumably, different sites and mechanisms of sequestration are involved.