Multiple sclerosis immunopathic trait and HLA-DR(2)15 as independent risk factors in multiple sclerosis

We analysed HLA haplotypes in pairs of 78 sporadic multiple sclerosis (MS) patients and 78 healthy siblings. The presence of 2 oligoclonal IgG bands, detected by immunoblotting of the cerebrospinal fluid in healthy siblings, has previously been defined as MS immunopathic trait (MSIT), based on a cut-off derived from healthy unrelated volunteers. The frequency of MSIT was 17.9% (n=14/78 siblings). The HLA-DR(15)2 allelle was present in 21.4% (n=3/14) of the siblings with MSIT, in 40.6% (n =26/64) of the siblings without MSIT, and in 59% (n =46/78) of the patients with clinically-definite (CD) MS. The distribution of zero, one or two HLA-DR(2)15 alleles was significantly skewed towards a lower allelle count in the siblings with MSIT compared with the group of unrelated siblings with MS (P=0.002), and also lower than their related siblings with MS (P=0.1). These results suggest that the MS susceptibility gene, HLA-DR(2)15 type, does not induce MSIT, and conceivably these are two separate risk factors in the development of MS. The effect of HLA-DR(2)15 and MSIT in sporadic MS appears to be synergistic. Multiple Sclerosis 2007; 13: 441-445. http://msj.sagepub.com

A linkage study in two families with multiple sclerosis and healthy members with oligoclonal CSF immunopathy

We studied two extended families in which not only multiple sclerosis (MS) segregates, but also approximately 18% of the cerebrospinal fluid (CSF) investigated blood relatives have ‘MS immunopathic trait’, an oligoclonal CSF immunopathy similar to that seen in MS, but with no neurological symptoms. Both families fit a genetic model for autosomal dominant inheritance for MS immunopathic trait, although with reduced penetrance in family A. In order to identify genetic factors of importance for the development of MS immunopathic trait, we performed a genome scan using the CHLC/Weber Screening Set (ver 6A), with 285 successful markers, to test the hypothesis that a single gene is causing the MS immunopathic trait in these families. Using a parametric method, we identified regions with suggestive linkage at chromosome 6q12 with a LOD-score of 2.4, putative linkage with LOD-score 1.5 at chromosome 6p21 (HLA region), putative linkage at chromosome 12q24 with a LOD-score of 1.7 and suggestive linkage at chromosome 19q13.2 with a LOD-score of 1.8. The LOD-score at chromosome 19q13.2 increased to 2.2 when only family A was analysed. In family A, all MS patients and two of five individuals with MS immunopathic trait had HLA DRB1*(15) and in family B, all blood relatives had the rare HLA type DRB1*0103, which is associated with other autoimmune diseases. We suggest that DRB1*0103 is a necessary but not sufficient condition for the susceptibility for MS immunopathic trait in this family.

Kidney transplantation--a 46-year experience from the Transplant Institute, Sahlgrenska University Hospital, Gothenburg, Sweden

The limiting factor in organ transplantation is the availability of organs. Ongoing work to improve donation rates both at the public and the organizational level in donating hospitals is essential. We also think that encouragement of live donation is important, and the possibility of ABO incompatible transplantation has increased the number of LD transplantations. The one-year graft survival rate is excellent and focus has shifted towards achieving long-term results to reduce the attrition rate. There is also an increasing interest in studying and working to reduce comorbidities on a long-term basis and thus, improve survival rates and recipient quality of life.

Blood group A(1) and A(2) revisited: an immunochemical analysis

BACKGROUND AND OBJECTIVE

The basis of blood group A(1) and A(2) phenotypes has been debated for many decades, and still the chemical basis is unresolved. The literature generally identifies the glycolipid chemical differences between blood group A(1) and A(2) phenotypes as being poor or no expression of A type 3 and A type 4 structures on A(2) red cells, although this assertion is not unanimous.

MATERIALS AND METHODS

Using purified glycolipids and specific monoclonal antibodies, we revisited the glycolipid basis of the A(1) and A(2) phenotypes. Purified glycolipids were extracted from four individual A(1) and four individual A(2) blood units. One blood unit from an A weak subgroup was also included. Monoclonal anti-A reagents including those originally used to define the basis of A(1) and A(2) phenotypes were used in a thin layer chromatography - enzyme immunoassay to identify the presence of specific glycolipids.

RESULTS

A type 3 glycolipid structures were found to be present in large amounts in all phenotypes. In contrast, the A type 4 glycolipid structure was virtually undetectable in the A(2) phenotype, but was present in the A(1) and A subgroup samples.

CONCLUSION

The major glycolipid difference between the A(1) and A(2) phenotypes is the dominance of A type 4 glycolipids in the A(1) phenotype.

Glycolipid studies in small intestine and pancreas of alpha1,3-galactosyltransferase knockout miniature swine: alpha1,3GALT-KO animals lack alphaGAL antigens and contain novel blood group H compounds

BACKGROUND

To avoid hyperacute rejection of xeno-organs, alpha1,3-galactosyltransferase knock-out (GalT-KO) pigs have been produced. However, Galalpha1,3Gal (Gal) determinant elimination may expose cryptic carbohydrate antigens and/or generate new antigens that might interfere with the human immune response.

METHODS

Glycolipids isolated from small intestine and pancreas of two GalT-KO and one wild-type (WT) pig were tested for immune reactivity with antibodies on thin-layer chromatograms after separation by high-performance liquid chromatography, and selected fractions were analysed by proton NMR spectroscopy.

RESULTS

Immunostaining using purified human anti-Gal Abs revealed that tissues from WT animals express large amounts of Gal-antigens whereas GalT-KO tissues lacked these antigens. Proton NMR spectroscopy on small intestine fractions revealed both linear and branched nona- and decaglycosylceramides, respectively, with terminal Gal-epitopes. In corresponding GalT-KO fractions, Gal-epitopes seemed to be replaced by terminal alpha1,2fucoses. Two novel branched blood group H compounds was found in the GalT-KO intestine.

CONCLUSIONS

The structural complexity of alphaGal-terminating antigens in the WT organs is very high. Knockout of alpha1,3GalT by gene-targeting results in elimination of Gal-determinants. In addition structurally novel alpha1,2fucose-terminated blood group H compounds were identified in the GalT-KO tissue. These compounds are not expected to be recognized by the human immune system.

Successful ABO-incompatible liver transplantation using A2 donors

INTRODUCTION

The longer waiting time for a liver graft among patients with blood group O makes it necessary to expand the donor pool for these patients. We herein have reported our experience with ABO-incompatible liver transplantation using A(2) donors to blood group O recipients.

PATIENTS AND METHODS

Between 1996 to 2005, 10 adult blood group O recipients received 10 A(2) cadaveric grafts. Mean recipient age was 52 +/- 7.7 years (mean +/- SD). The initial immunosuppression was induction with antithymocyte globulin (n = 2), interleukin-2-receptor antagonists (n = 3), or anti-CD20 antibody (rituximab, n = 1), followed by a tacrolimus-based protocol. No preoperative plasmapheresis, immunoadsorption, or splenectomies were performed.

RESULTS

Patient and graft survival was 10/10 and 8/10, respectively, at 8.5 months median follow-up (range 10 days to 109 months). Two patients were retransplanted because of bacterial arteritis (n = 1) and portal vein thrombosis (n = 1). The six acute rejections, which occurred in four patients, were all reversed by steroids or increased tacrolimus dosages. The pretransplant anti-A titers against A(1) red blood cells were 1:128 (NaCl technique) and 1:8 to 1024 (IAT technique). The maximum postoperative titers were 1:64 to 4000 (NaCl) and 1:256 to 32000 (IAT).

CONCLUSION

The favorable outcome of A(2) to O grafting, with a patient survival of 10/10 and graft survival of 8/10, makes it possible to consider this blood group combination also in nonurgent situations. There was no hyperacute rejection or increased rate of rejections. Anti-A/B titer changes seem to not play a significant role in the monitoring of A(2) to O liver transplantation.

Successful combined partial auxiliary liver and kidney transplantation in highly sensitized cross-match positive recipients

Combined liver and renal transplantations can be performed against a positive cross-match, indicating that the liver protects the kidney from the harmful HLA antibodies. This led us to the hypothesis that a partial auxiliary liver graft may have a similar protective effect when performed together with the kidney in highly sensitized patients. Seven patients, with broadly reacting HLA antibodies and positive crossmatches, were transplanted with a partial liver and a kidney from the same donor. In one of the cases a living donor was used. We performed lymphocytotoxic and flow cross-matches before and after the transplantation. Cross-matches turned negative after grafting in five of seven cases. The kidney function was excellent, without rejections, during the follow-up (24-60 months) in these patients. In two cases the cross-match remained positive after transplantation, one with a never-functioning renal graft and the other with an early graft failure, probably due to humoral rejection. A simultaneous transplantation of a partial auxiliary liver graft from the same donor, with the sole purpose of protecting the kidney from harmful lymphocytotoxic antibodies, can be performed successfully despite a positive cross-match and may thus be a new option of treatment for highly sensitized patients waiting for a kidney transplant.

Novel glycolipid variations revealed by monoclonal antibody immunochemical analysis of weak ABO subgroups of A

BACKGROUND AND OBJECTIVES

The chemical basis of the subgroups of A is largely unknown. We used thin-layer chromatography immunochemical staining techniques together with a range of characterized monoclonal reagents to analyse glycolipids isolated from a variety of weak subgroups.

MATERIALS AND METHODS

Glycolipids isolated from red cells collected from nine genetically defined individuals of the rare subgroups of A, including a novel A(3) allele (A(2) 539G>A) not described previously, were subjected to a highly sensitive thin-layer chromatographic immunochemical analysis.

RESULTS

Semicharacterized monoclonal antibodies revealed that, in addition to the expected quantitative differences between common phenotypes and the weak subgroups, qualitative glycolipid differences (or at least an apparent qualitative basis), caused by major changes in the ratios of different structures exist. Specifically it was found that the weakest A-expressing samples (A(el) phenotype) appeared to express an unusual A structure in the 8-12 sugar region. Variable expression of several structures in one of the A weak samples were suggestive of novel blood group A structures.

CONCLUSIONS

Although no structural characterization could be undertaken, the results are clearly indicative that the variant glycosyltransferases of the rare ABO subgroups are not only inefficient, but they may potentially synthesize novel ABO structures.

Molecular genetic analysis of the nested Drosophila melanogaster lamin C gene

Lamins are intermediate filaments that line the inner surface of the nuclear envelope, providing structural support and making contacts with chromatin. There are two types of lamins, A- and B-types, which differ in structure and expression. Drosophila possesses both lamin types, encoded by the LamC (A-type) and lamin Dm0 (B-type) genes. LamC is nested within an intron of the essential gene ttv. We demonstrate that null mutations in LamC are lethal, and expression of a wild-type LamC transgene rescues lethality of LamC but not ttv mutants. Mutations in the human A-type lamin gene lead to diseases called laminopathies. To determine if Drosophila might serve as a useful model to study lamin biology and disease mechanisms, we generated transgenic flies expressing mutant LamC proteins modeled after human disease-causing lamins. These transgenic animals display a nuclear lamin aggregation phenotype remarkably similar to that observed when human mutant A-type lamins are expressed in mammalian cells. LamC aggregates also cause disorganization of lamin Dm0, indicating interdependence of both lamin types for proper lamina assembly. Taken together, these data provide the first detailed genetic analysis of the LamC gene and support using Drosophila as a model to study the role of lamins in disease.

Characterization of the humoral immune response in two paediatric patients transplanted with split livers from ABO-incompatible living-related donors: appearance of cytomegalovirus-induced ABO antibodies

Two blood group O paediatric patients, 12 and 6 months old, were transplanted with liver segments from their blood group A2Le (a(-)b+) Se and blood group A1Le (a(-)b+) Se fathers, respectively. Recipient anti-A antibody titres were reduced prior to transplantation by blood exchange. Both patients had rejection episodes in the post-transplant period that were reversed by anti-rejection therapy. No anti-A antibody titre rise occurred concomitant with these rejections. Postoperatively both patients had cytomegalovirus (CMV) infections, and simultaneous with these infections, a strong increase in anti-A antibody titres was seen, but no rejection occurred. The anti-A antibody titre increase seemed to be specific for A antigens, because the anti-B and anti-alphaGal (anti-pig) antibody titres did not show any changes. CMV infection is a serious cause of morbidity and mortality in immunosuppressed patients, and the virus can influence glycosylation of infected cells. Whether this can explain the importance of the infection in relation to the increase in titre remains to be elucidated.

Complement activation in prestorage leucocyte-filtered plasma

Complement activation and generation of pro-inflammatory cytokines occur during storage of blood components. Prestorage leucocyte filtration of platelet concentrates and red cells diminishes the accumulation of leucocyte-derived cytokines during storage, however, transfusion reactions are not eliminated. We investigated inflammatory mediator release during storage of plasma and whole blood and the effect of prestorage leucocyte filtration of plasma. Twenty-four blood units were collected from healthy blood donors and stored for 35 days. Eight units were stored as whole blood, eight units as plasma and eight units as prestorage filtered plasma. Samples were collected weekly for analyses of potassium, leucocytes, free plasma haemoglobin, complement activation (C3a and SC5b-9) and pro-inflammatory cytokines [interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF)-alpha]. Elevated levels of C3a and SC5b-9 were registered in filtered plasma, from the beginning of storage. C3a levels increased during storage. There was a higher rate of change during storage in C3a (P < 0.01) and SC5b-9 (P < 0.05) in plasma compared with filtered plasma. Interleukin (IL)-8 is released in whole blood. The cytokine levels generated in plasma and filtered plasma were low. Complement activation is present in whole blood, plasma and filtered plasma during storage. Prestorage filtration of plasma activates the complement cascade but does not influence cytokine generation.

ABO-incompatibility in solid organ transplantation

The most important transplantation antigen system in solid organ transplantation is the ABO histo-blood group system. Crossing the ABO barrier in solid organ transplantation is usually not done except for emergency liver transplantations. Early experiences of crossing the ABO barrier in renal transplantation were very disappointing. In the 1970s, clinical trials were started transplanting kidneys of subgroup A2 into blood group O recipients. The tissues of the A2 subgroup expresses reduced amount of A antigens compared to subgroup A1 and the recipients had no special pretreatment and standard immunosuppression. A number of early graft losses were experienced but the trial also resulted in several long time surviving grafts. A few centres have adapted the concept of A2 to non A kidney transplantations with successful results, when the recipient anti-A titres are low or reduced prior to transplantation. In the early 1980s one group successfully transplanted A1 and B kidneys from living related donors across the ABO-barrier using an immunosuppressive protocol consisting of quadruple drugs and splenectomy and this protocol was adapted by a few other groups. In Japan, where cadaver donors are available in very limited number, the largest number of ABO-incompatible transplantations have been performed. Altogether more than 300 ABO-incompatible kidney transplantations have been performed in more than 40 centres since 1989. ABO-incompatible liver transplantations have been performed mainly in emergency cases and the results have generally been inferior to ABO-compatible grafts. In children below the age of three years, liver transplantations across the ABO-barrier have been quite successful especially with living related donors. Very few ABO-incompatible heart/heart-lung/lung-transplantations have been reported with a few successful cases, but the majority have been failures. Recently a series of ABO-incompatible heart transplants performed in small children have been reported with a high success rate.

Blocking of human anti-pig xenoantibodies by soluble GAL alpha 1-3Gal and Gal alpha 1-2Gal disaccharides; studies in a pig kidney in vitro perfusion model

Depletion of anti-pig xenoantibodies reduces cell cytotoxicity of human serum to pig endothelial cells and lymphocytes. The aim of this study was to test, in a pig kidney xenoperfusion model, the ability of soluble alpha Gal terminated disaccharides to prevent the hyperacute rejection process in an organ. Porcine kidneys were perfused with whole human blood lacking saccharide and blood supplemented with Gal alpha 1-3GAL, Gal alpha 1-2Gal and lactose. Parameters evaluated were, urine production, renal blood flow, vascular resistance, renal clearance, blood cell counts, xenoantibody titers, complement activation and histopathology. The blood flow was higher in the Gal alpha 1-3Gal (155 +/- 31 ml/min x 100 g-1 kidney tissue) group compared to Gal alpha 1-2Gal (138 +/- 16), lactose (92 +/- 78) and controls (69 +/- 16), When calculated as percent of the blood flow value at 1 min, the blood flow at 30 min was 157% for the Gal alpha 1-3Gal and for 187% the Gal alpha 1-2Gal. The corresponding values for the lactose and control groups were 102% and 74%, respectively. Urine production in the lactose/control groups was lower (0.7 ml/min x 100 g-1 kidney tissue) compared to Gal alpha 1-3Gal (3.0) and Gal alpha 1-2Gal (3.7). Urine sodium excretion was reduced in the lactose/control groups, compared to the Gal alpha alpha 1-groups during the perfusions. An increase in urine potassium excretion was found in the Gal alpha alpha 1-groups while a reduction occurred in the lactose/control experiments. An initial 40-50% reduction in platelet count was observed in all groups while the leukocyte count showed a continuous decrease. Immunohistochemistry revealed less deposition of IgM, IgG, C3 and C1 q in the Gal alpha alpha 1-saccharide groups compared to the lactose/control groups. Soluble Gal alpha a1-disaccharides improved both functional and histological parameters. However, significant pathological changes were still present indicating that this approach to inhibit HAR must be used in combination with additional therapeutic approaches such as solid phase xenoantibody immunoadsorption and blocking of complement activation.

Histo-blood group A antigen expression in pig kidneys--implication for ABO incompatible pig-to-human xenotransplantation

OBJECTIVE

There is a relative shortage of donor organs for clinical transplantation, and the use of animal organs is being considered. A clinical trial was performed connecting pig kidneys to the circulation of a dialysis patient.

MATERIAL AND METHODS

A pig kidney was, after plasmapheresis, extracorporeally connected to the circulation of a volunteer dialysis patient. The patient was of blood group B and the pig of blood group A.

RESULTS

The experiment gave rise to a strong humoral immune response where the xenoantibodies were shown to be of immunoglobulin G (IgG), IgM and IgA immunoglobulin classes, recognizing mainly the Gal alpha1-3Gal epitope and the anti-A antibodies was exclusively of IgM type, recognizing the blood group A trisaccharide. Immunohistological examinations of blood group A pig kidneys revealed that blood group A antigens are located in the distal tubules, thin and thick tubules of Henle and the epithelium of the collecting ducts but absent in proximal tubules, glomeruli, large vessels and capillaries. In the perfused kidney, a patchy destruction of tubular cells was found and these segments stained positive for blood group A antigens and had a codeposition of human IgM antibodies and complement components. Tubular segments which were apparently normal were all negative for blood group A antigens but strongly expressed the Gal alpha1-xenoantigen.

CONCLUSION

In this patient, challenged simultaneously with carbohydrate antigen epitopes representing both the ABO and the xenobarrier, the humoral immune response differed concerning the immunoglobulin classes induced. The low remaining anti-A titre after plasmapheresis was probably sufficient to cause destruction of A antigen-positive tubular cells, while the corresponding Gal alpha1-xenoantigen-positive cells were structurally intact. This case confirms that in future xenotransplantation, matching for the ABO system has to be undertaken in the same way as in human allotransplantation.

Lack of antibody production against Hanganutziu-Deicher (H-D) antigens with N-glycolylneuraminic acid in patients with porcine exposure history

The significance of non-alphagalactosyl antigens remains unclear in pig-to-primate xenotransplantation. Hanganutziu-Deicher (H-D) antigens with terminal N-glycolylneuraminic acid (NeuGc) are widely expressed on endothelial cells of mammalian species, with the exception of humans. As baboons and monkeys also express H-D antigens, a pig-to-non-human primate experimental model cannot resolve the question of whether H-D antigens can elicit a potent humoral response in human recipients. The purpose of this study was to elucidate the clinical significance of H-D antigens by examining the sera from patients who have been previously exposed to porcine tissue. After the digestion of porcine aortic endothelial cells (PAEC) by neuraminidase, NeuGc and N-acetylneuraminic acid (NeuAc) were quantitated by HPLC. IgG and IgM antibody levels against H-D antigens were measured by NeuGc-GM3-coated ELISA plates in the sera of patients who had undergone ex vivo kidney perfusion 1 to 3 weeks and 2 years previously (n=2) or had been injected with fetal porcine islets 2 months previously (n= 10). HPLC determined that 9.7x 10(7) NeuAc and 6.3x 10(7) NeuGc residues per cell were released from PAEC by neuraminidase, while 25.7x 10(7) NeuAc and an undetectable level of NeuGc were released from human aortic endothelial cells (HAEC). No significant elevation of IgG or IgM antibody levels against NeuGc-GM3 was observed in sera from patients with a history of porcine exposure. Considering the active production of antibody against the foreign galactosyl antigens after pig-to-human xenotransplantation, some production of antibodies against the equally foreign H-D antigens would be expected, because large amounts of NeuGc terminated saccharides are present in the pig endothelial cell surface. However, no production of antibodies directed to H-D antigens could be found in patients exposed to porcine tissue. Further studies are warranted to explain why H-D antigens do not elicit a significant antibody production.

Esomeprazole provides improved acid control vs. omeprazole In patients with symptoms of gastro-oesophageal reflux disease

BACKGROUND

Esomeprazole (Nexium) is a new proton pump inhibitor for the treatment of acid-related diseases.

METHODS

In this double-blind crossover study, 38 patients with gastro-oesophageal reflux disease (GERD) symptoms were randomized to esomeprazole 40 and 20 mg and omeprazole 20 mg once daily for 5 days. On day 5 of each dosing period, 24-h intragastric pH and pharmacokinetic variables were measured.

RESULTS

Thirty-six patients aged 29-58 (mean 45) years completed the study. Esomeprazole 40 and 20 mg maintained intragastric pH > 4 for (mean) 16.8 and 12.7 h, respectively, vs. 10.5 h for omeprazole 20 mg (P < 0.001 and P < 0. 01). Twenty-four-hour median intragastric pH was significantly higher with esomeprazole 40 mg (4.9) and 20 mg (4.1) than with omeprazole 20 mg (3.6) (P < 0.001 and P < 0.01). Area under the plasma concentration-time curve (AUC) was 80% higher for esomeprazole 20 mg vs. omeprazole, while that for esomeprazole 40 mg was more than five times higher (each P < 0.0001). Interpatient variability in intragastric pH and AUC was less with esomeprazole than with omeprazole. Esomeprazole was well tolerated and there were no safety concerns.

CONCLUSIONS

Esomeprazole provides more effective acid control than omeprazole, with reduced interpatient variability, thereby offering the potential for improved efficacy in acid-related diseases.

Characteristics of secondary oesophageal peristalsis in operated and non-operated patients with chronic gastro-oesophageal reflux disease

BACKGROUND AND AIMS

Secondary oesophageal peristalsis contributes to oesophageal volume clearance and may be impaired in a significant proportion of patients with chronic gastro-oesophageal reflux disease (GORD). This study aimed to investigate the triggering of secondary peristalsis in chronic GORD patients compared to those previously operated on with anti-reflux surgery.

PATIENTS AND METHODS

Healthy volunteers, chronic GORD patients with proven oesophagitis and patients successfully operated on with anti-reflux surgery (> 3 years ago) were investigated. Secondary peristalsis was elicited by oesophageal distension by a bolus of air (10 ml) injected rapidly into the mid-portion of the oesophagus. The peristaltic characteristics in the distal oesophagus were assessed by use of stationary manometry.

RESULTS

The primary peristaltic amplitude in the distal third of the oesophagus was significantly higher (P < 0.002) in the non-operated GORD cases than in those recruited for surgery. Furthermore, a difference in the frequency of failed primary peristalsis was revealed (2.1 versus 8.4%) between the non-operated and operated patients. Secondary peristalsis occurred in 65 +/- 13.2% (mean +/- SE) of the healthy subjects on stimulation, which was a higher figure than in the GORD patients. In patients investigated after successful anti-reflux surgery, a secondary peristaltic wave was elicited in only 26 +/- 7.2% of the attempts, which was significantly lower than the 46 +/- 7.7% seen in non-operated GORD patients (P < 0.05). A direct comparison between motor characteristics of primary and secondary peristalsis revealed that the latter amplitudes were significantly lower both in the non-operated and in the operated cases (P < 0.005).

CONCLUSIONS

The triggering of secondary peristalsis seems to be impaired in chronic GORD patients. Investigating similar patients > 3 years after successful anti-reflux surgery revealed an even lower prevalence of secondary peristaltic waves, implying persistence of the abnormality after surgery and consistent with other evidence that GORD is associated with a primary defect in oesophageal motor function.

Typing for the human lewis blood group system by quantitative fluorescence-activated flow cytometry: large differences in antigen presentation on erythrocytes between A(1), A(2), B, O phenotypes

BACKGROUND

Lewis phenotyping by hemagglutination is an unreliable routine method for Lewis antigen designation. Now genomic typing of the Lewis gene is available. Additionally, flow cytometry has been used for typing. We wanted to compare the results of Lewis typing in healthy individuals using the three methods.

MATERIALS AND METHODS

Ninety-three randomly selected plasma donors were genotyped for inactivating Secretor (FUT2) G428A and Lewis (FUT3) T59G, T202C, C314T, G508A and T1067A point mutations. All Le(a+b-) individuals (nonsecretors) were homozygous for the FUT2 G428A mutation and all Le(a-b-) individuals had inactivating mutations on both FUT3 alleles. Fixed erythrocytes were analyzed by fluorescence-activated flow cytometry and the results were compared with hem- agglutination and genotypic data. Antigen availability was expressed as median fluorescence intensity and as percentage positive cells with fluorescence intensities > or =10(2).

RESULTS

Using an anti-Le(a) reagent a mean of 99% of erythrocytes from Le(a+b-) individuals and 1% of erythrocytes from Le(a-b-) or Le(a-b+) individuals were stained positive. Using an anti-Le(b) reagent, a mean of 71% of erythrocytes from A(1), 95% from B and 99% from O and A(2) Le(a-b+) individuals and less than 10% of erythrocytes from Le(a-b-) or Le(a+b-) individuals were stained positive. After papain treatment 100% of the erythrocytes from A(1) and A(1)B Le(a-b+) individuals stained positive without increase in background staining. The flow cytometric technique revealed large differences in staining intensities, within each ABO Le(a-b+) subgroup which was not directly correlated to plasma donation frequencies nor to Secretor or Lewis genotypes.

CONCLUSION

Flow cytometry may prove valuable as a Lewis blood group typing technique but also as a research tool when investigating Lewis phenotypes of human erythrocytes.

Tailoring antireflux surgery: A randomized clinical trial

A hypothesis has been formulated that mandates the adjustment of antireflux surgery to either a total or a partial wrap depending on the motor function of the esophagus to avoid dysphagia and other obstructive complaints. This hypothesis has been tested in a randomized, clinical trial where 106 chronic gastroesophageal reflux patients were allocated to either a total Nissen-Rossetti (n = 53) or a Toupet partial posterior (n = 53) fundoplication, irrespective of their preoperative esophageal motor function. All patients were followed at least 3 years, during which time none had a relapse of moderate to severe reflux symptoms. Motor dysfunctions defined as peristaltic amplitude </= 30 mmHg in the distal third and failed primary peristalsis with or without > 20% simultaneous contractions were noted in 67 patients preoperatively, but these patients did not have a specific symptom profile (e.g., dominated by obstructive symptoms) nor did seven patients with "aperistaltic esophagus." The incidence of dysphagia decreased from 20% preoperatively to 8% (mild) at 3 years after the operation with no difference between the surgical procedures. We were unable to demonstrate a relation between preoperative manometric findings and postoperative symptoms when assessed in the total group or when subdivided by the type of fundoplication (r < 0.3). Flatulence occurred more frequently among those with a total fundic wrap (p < 0.01). When patients representing motor dysfunction (see above) were specifically analyzed, we again observed no difference in outcome between those having a total or a partial fundic wrap. In conclusion, the concept of tailoring antireflux surgery based on the preoperative motor function of the esophagus in patients with chronic gastroesophageal reflux disease was not supported by the results of this clinical trial.

Mechanism of action of antireflux procedures

BACKGROUND

To define the clinical role of antireflux surgical procedures a proper understanding of their mode of action is required. The aim of this study was to investigate the impact of total or posterior partial fundoplication on the function of the lower oesophageal sphincter (LOS) in the basal state as well as during stimulation.

METHODS

Patients with chronic reflux (n = 24) were randomized either to a total fundic wrap or to a posterior partial (Toupet) fundoplication. Basal LOS function was investigated as well as the response to inhibitory stimuli 4 years after operation. Inhibitory stimulation was elicited by water swallows and by gas distension (750 ml air insufflation into the stomach).

RESULTS

Basal LOS tone was substantially higher (P = 0.01) after a total than a partial wrap, as was the nadir pressure after water swallows (10.1 versus 3.4 mmHg). Body position did not affect this difference. Transient LOS relaxations occurred only occasionally in the basal state. The frequency of transient LOS relaxation increased somewhat during the first 10 min of stomach distension with more occurring in patients who underwent a Toupet procedure. Common oesophagogastric cavities were more often seen in this latter group of patients after gas distension of the stomach.

CONCLUSION

These physiological observations on the LOS after total and posterior partial fundoplication explain the observed clinical differences in favour of the latter operation. The partial fundoplication seems to restore the physiology of the gastro-oesophageal junction more adequately, allowing air to be vented from the stomach without jeopardizing the antireflux barrier.

alpha-Gal epitopes in animal tissue glycoproteins and glycolipids

alpha-Gal terminated saccharides are present on the cell surface both as glycolipids and glycoproteins in all mammals except Old World monkeys and humans. The structural diversity among identified saccharides terminated by this epitope in animal tissues is steadily increasing. The majority of these saccharides have the alpha-Gal linked to lactosamine but other core saccharides exist. The alpha-Gal terminated saccharides are recognized by the immune system as a specific antigen and antibodies directed to the alpha-Gal, which do not cross-react with the classic blood group B trisaccharide, are found in man and Old World monkeys. Similar to other complex carbohydrate cell surface antigens, the alpha-Gal epitope is heterogeneously distributed in different organs and in different cells within an organ. It is present on the vascular endothelium and it is the primary target for human naturally occurring antibodies following pig to primate/man xenotransplantation leading to hyperacute rejection of the graft. Important for the future will be to further structurally characterize this antigen system, its cellular/subcellular distribution, and to identify possible of additional glycosyltransferases, related to the already described alpha 1,3galactosyltransferase that may explain the structural diversity. Such information will be of importance in the studies of, for example, the pathogenesis of autoimmune diseases and for the production of genetically modified pigs to prevent xenograft rejection.

No evidence of pig DNA or retroviral infection in patients with short-term extracorporeal connection to pig kidneys

BACKGROUND

The xenotransplantation of organs and tissues, in particular those from pigs, is viewed as a means to alleviate the shortage of human donor organs and cells available for transplantation and also as a therapy for other diseases. The potential microbiological hazards of xenotransplantation have recently attracted much attention. One concern is over pig endogenous retroviruses (PERV). Until the possible consequences of infection by PERV are better understood it is unlikely that a significant number of porcine xenotransplants will proceed. However, a small number of patients have already been treated with or exposed to living porcine cells or tissue, and investigation of these patients may provide valuable information.

METHODS

We took serial blood samples from two renal dialysis patients whose circulation had been linked extracorporeally to pig kidneys and tested them for pig DNA and PERV DNA by nested PCR. The patients' plasma was also tested for neutralising antibodies to two anthropotropic PERV strains.

FINDINGS

Having established that the nested PCRs could detect single molecules of target sequence, we analysed DNA isolated from patients' peripheral blood mononuclear cells. We found no evidence of pig or PERV DNA in either patient, even in samples taken as early as 6 h after the perfusion. Furthermore, we found no evidence of seroconversion for PERV-specific antibodies.

INTERPRETATION

The absence of porcine cells in the circulation of both patients, even in the samples taken soon after the perfusion experiment, suggests that any porcine cells dislodged from the kidney became rapidly sequestered from the circulation. Since cell-to-cell contact increases the efficiency of infection of PERV this removal of porcine cells may increase the risk of transmission of PERV to the xenograft recipient. We did not, however, detect indications of infection by PERV by PCR or neutralisation assay. The genetic and serological methods described here will be useful for detection of possible PERV infection in other patients.

Extracorporeal ("ex vivo") connection of pig kidneys to humans. III. Studies of plasma complement activation and complement deposition in the kidney tissue

The complement system is one of the important factors involved in the hyperacute rejection of xenografts. This report deals with the activation of the complement system in a clinical trial where pig kidneys were extracorporeally connected to two volunteer dialysis patients who were pretreated with plasmapheresis in order to substantially reduce anti-pig xenoantibodies. The clinical data of the perfusion experiments and the patients humoral immune response to pig xenoantigens have been reported in detail (Xenotransplantation 1996; 3:328-339, 340-353). Three consecutive daily plasmapheresis treatments of the patients reduced the plasma complement protein (C3, C4, and C5) concentrations to 8-27% of the baseline values. The perfusion of the pig kidney connected to patient 1 was terminated at 65 min due to graft rejection and this patient was not hemodynamically affected by the experiment. The second experiment was terminated at 15 min due to an anaphylactic like reaction of the patient. In patient 1 a slight reduction of plasma C3, C4, and C5 and an increase of C5a and SC5b-9 occurred, while C3a decreased during the perfusion. Patient 2 had an increase of all complement parameters, most prominent for C4d and SC5b-9, which occurred concomitant with the appearance of the anaphylactic like side effects. In general, plasma levels of PMN elastase, IL6 and IL8 increased in both patients during the perfusion. Immunohistochemical investigation of the kidney tissues revealed deposition of human complement factors C1q, C4c, and C3c in a congruent pattern with the vasculature of the kidney in patient 1. In kidney 2 only trace amounts of C1q and C3c were found. Both kidneys were negative for properdin. Therefore, in this experimental set up with extracorporeal connection of pig kidneys to the human circulation the human complement cascade is activated mainly through the classical pathway.

Characterisation of human natural anti-sheep xenoantibodies

Currently, the pig species is regarded as the most likely organ donor for human xenotransplantation in the future. However, it cannot be granted that the pig will be the optimal species of choice. We have studied human anti-sheep antibodies in comparison with anti-pig antibodies. The anti-sheep lymphocytotoxic and hemagglutination titers were in the range 8 to 128 and 2 to 32, respectively, in single individuals, which were considerably lower than the anti-pig titers of these individuals. Perfusion of sheep kidneys with human blood reduced the anti-sheep xenoantibody titers to zero as measured by lymphocytotoxic, hemagglutination, and sheep aortic endothelial cell antibody binding assays. The perfused kidneys showed generalised depositions of human IgM and C3c in the vascular tree and focal depositions of C1q and fibrin. Obliteration of capillaries by human platelets and polymorphonuclear cells were observed. Total neutral glycolipid fractions were isolated from sheep intestinal, pancreatic, and kidney tissues. By using a chromatogram binding assay, a monoclonal anti-Forssman antibody identified a single compound with five sugar residues in all organs. Several glycolipid bands were stained in all organs by the Gal(alpha)1-specific lectin I-B4 from Griffonia (Bandeiraea) Simplicifolia. A human AB serum pool showed staining by both IgG and IgM antibodies of the Forssman and Gal(alpha)1-terminating components as well as some other, not structurally identified, components. The Forssman and Gal(alpha)1-reactivity in human sera could be eliminated by immunoadsorption using Forssman and Gal(alpha)1-3Gal-immunoadsorbent columns, respectively. Immunostaining of sheep kidney tissue sections showed the presence of Gal(alpha)1-terminating epitopes by immunoperoxidase and immunogold silver staining techniques. Proximal convoluted tubules showed a strong staining, while thin loops of Henle, collecting ducts, urothelium, and vessels showed a weaker staining. Distal convoluted tubules and thick loops of Henle were completely negative. In summary, human serum contains anti-sheep xenoantibodies reacting mainly with the Forssman and Gal(alpha)1-determinants in sheep tissues and the anti-sheep antibody titers are lower than the corresponding anti-pig titers.

An ELISA technique for quantitation of human xenoantibodies binding to pig cells: application in patients with pig kidneys extracorporeally connected to the circulation

A quantitative ELISA technique for determination of human anti-pig xenoantibody number in serum samples has been established using pig lymphocytes and pig/rabbit erythrocytes as target cells and a pool of serum from human blood group AB donors. The number of low affinity antibodies binding to the cells was determined by quantitation following the use of aqueous washing of the cells and separation of bound and unbound antibodies with the phthalate oil method. The efficiency of different soluble Gal(alpha)1-3Gal-terminating di- and tri-saccharides to inhibit antibody binding was tested and found to vary between 70-90% at a saccharide concentration of 10 mg/ml. The assay was used to evaluate the antibody changes in two patients who, after plasmapheresis treatments, had pig kidneys extracorporeally connected to their blood circulation. The number of anti-pig IgM/IgG antibodies bound to each pig lymphocyte were reduced from 5,600/13,200 to 1,300/3,100 in patient 1 and from 1,200/6,500 to 500/2,100 in patient 2 by three consecutive daily plasmapheresis treatments. Although the lymphocytotoxic titers were reduced to very low levels, the antibody numbers still present in the blood of patient 1 caused a hyperacute rejection of the pig kidney. However, the antibody levels in patient 2 did not cause rejection of this kidney during 15 min perfusion time. A strong anti-pig antibody response 3 weeks after the perfusion experiment was found in patient 1 as shown by 27,600/245,300 IgM/IgG molecules bound to pig lymphocytes corresponding to an increase of lymphocytotoxic titer from 8 to 512. The second patient showed a much weaker immune response with 1,400/19,800 IgM/IgG antibodies corresponding to a lymphocytotoxic titer increase from 8 to 32. The use of this quantitation technique enables more accurate investigation of antibody binding to xenogenic target cells than conventional titration techniques.

Does oesophageal motor function improve with time after successful antireflux surgery? Results of a prospective, randomised clinical study

MAIN OBJECTIVE

There is a continuing debate whether motor abnormalities associated with gastro-oesophageal reflux disease (GORD) are primary phenomena or occur as a consequence of repeated injury caused by inflammation. To get new insights into mechanisms involved, patients were studied before and three years after effective and durable reflux control induced by two types of fundoplications.

PATIENTS AND METHODS

Thirty three consecutive patients with chronic GORD entered the trial. All patients had a clinical history of GORD assessed symptomatically, endoscopically, and by use of 24 hour pH-metry. Eighteen were randomised to a 180 degrees semifundoplication (Toupet) and 15 to a total fundic wrap (Nissen-Rossetti). Manometry was done preoperatively, six months, and three years after the operation assessing motor function in defined areas of the tubular oesophagus and lower oesophageal sphincter.

RESULTS

All patients had a proper control of GORD both when objectively and clinically assessed. Postoperatively, the resting tone of the lower oesophageal sphincter was significantly higher in the Nissen-Rossetti group (p < 0.05), and the intra-abdominal portion of the lower oesophageal sphincter was of identical length in the two groups. A significant increase in peristaltic amplitude in the middle and distal third of the oesophagus was recorded at long term follow up compared with the preoperative findings (p < 0.05), but there was no corresponding effect on propagation speed and duration of contraction. However, an increase in peristaltic amplitude and, as a tentative consequence, a significant decrease (p < 0.05) in the frequency of primary peristalsis was found only in patients operated on with a total fundic wrap.

CONCLUSION

Despite adequate and durable reflux control after fundoplication in patients with chronic GORD, no change was found in oesophageal motor function with time. The higher contraction amplitude and decreased frequency of failed primary peristalsis seen in patients having a total fundic wrap were thus most likely due to a mechanical outflow obstruction in the gastro-oesophageal junction. These results could therefore be interpreted in favour of the hypothesis that GORD is pathogenetically linked to a primary defect in oesophageal motor function.

Report from the HLA class II typing by PCR-SSP Multicentre Study

Results from 360 HLA-DR and -DQ 'low-resolution' typings with polymerase chain reaction sequence-specific primers (PCR-SSP), performed by nine laboratories, were analysed for their overall utility in routinely defining the HLA-DR1-DR18, DR51-DR53 and DQ1-DQ9 specificities in less than 2.5 h. Thirty EDTA blood samples and 10 DNA samples were distributed and analysed by each laboratory. DNA was extracted using a rapid bromide salt extraction protocol. Complete HLA-DR and -DQ typings were performed, three by three, on pre-aliquoted 96-tube PCR trays. When compared with reference typing, 351/360 (98%) correct DR typings were obtained, whereas 320/360 (89%) of the DQ phenotypes were correctly assigned. The time for three complete HLA-DR and -DQ 'low-resolution' typings, including DNA extraction, ranged from 2.0 h to 2.3 h. Unfortunately, an unusually high level of PCR amplification failures was observed (3%), probably due to diffusion and a significant volume loss from some of the pre-aliquoted primer mixes. Consequently, only 52% of the typings were without any amplification failure, and 0-2 amplification failures where found in 88% of the PCR-SSP typings performed. The number of HLA-DR-DQ retypings needed was 7 and 8%, respectively, reflecting the low number of typings where allelic identification was directly affected by the relatively high level of amplification failures in this study. Thus, a 91-98% success rate of correctly identified HLA-DR and -DQ alleles could be maintained, even under suboptimal typing conditions.

Blood spillage during salvage

Recovery of blood components by salvage was evaluated in a randomized laboratory investigation using donor whole blood. Three methods of salvage were studied; conventional red cell salvage, red cell salvage with continuous processing, and salvage by haemofiltration using recirculation through a 30,000-Da filter. Less than 10% of the haemoglobin was wasted during processing by all three methods. About half of the leukocytes were recovered with no significant difference between the techniques. The recovery of platelets was 15, 4 and 41% during salvage with conventional red cell centrifugation, continuous centrifugation processing and haemofiltration, respectively. In contrast with the other methods, haemofiltration gave a major recovery of albumin.

Complement activation during storage of whole blood, red cells, plasma, and buffy coat

BACKGROUND

The process of separating whole blood into components and the storage of blood components may cause the release of toxic metabolites from the complement cascade. The aim of this study was to determine whether the storage of blood components leads to the activation of the complement cascade and the release of anaphylatoxins.

STUDY DESIGN AND METHODS

Blood from 12 healthy volunteers was collected and stored either as whole blood or as components: red cells in saline-adenine-glucose-mannitol solution, plasma, and buffy coat. The concentrations of anaphylatoxins and other complement proteins in the various blood components were intermittently analyzed during a 5-week storage period.

RESULTS

Increasing levels of anaphylatoxins were demonstrated during the storage of whole blood and plasma. Elevated concentrations of the anaphylatoxins C3a and C5a were observed during the storage of whole blood. Increased C5a levels were observed after 7 days of storage. High concentrations of C3a were found in plasma after 14 days of storage. Low or non-detectable levels of C3a; C5a, and other complement components were found in red cells stores in saline-adenine-glucose-mannitol solution.

CONCLUSION

The study demonstrated activation of complement during the storage of whole blood and plasma but not in red cells in storage solution. The transfusion of larger volumes of stored whole blood or plasma may contribute to the risk of development of organ dysfunction. Therefore, it is advisable to use red cells in storage solution.

Influence of infant feeding and gluten intake on coeliac disease

OBJECTIVES

To study the impact of infant feeding habits and actual gluten intake on gluten induced enteropathy.

METHODS

A case-referent design, controlling for the HLA alleles conferring increased genetic risk, was used. All 164 siblings of 97 probands were investigated. Eighty five of the siblings, carrying the genes DQA1*0501-DQB1*02 conferring susceptibility for the disease, were investigated by interview, food recording, and taking a small intestinal biopsy sample. Eight cases of silent coeliac disease were found and these were compared with the 73 siblings in whom the diagnosis was excluded.

RESULTS

No statistically significant differences were found between cases and referents in terms of duration of breast feeding, age at introduction of cows' milk products, frequency of breast feeding after gluten introduction, and gluten consumption.

CONCLUSIONS

The studies factors may be of less importance for the development of gluten induced enteropathy.

Evidence for an expression of blood group A antigen on platelet glycoproteins IV and V

Blood group ABO antigens are known to be carried by several platelet glycoproteins (GP), e.g. GPIb, GPIIa, GPIIb, GPIIa and PECAM. Beside these proteins, we recently observed that blood group A antigen was also expressed on some other uncharacterized platelet proteins (70-90 kDa) having electrophoretic mobilities closely resembling those of GPIV and GPV. These findings prompted us further to characterize these latter ABO-expressing platelet proteins. By antigen capture ELISA, wherein the monoclonal antibodies (mAbs) CLB-IVC7 and CLB-SWI6 were used to hold the corresponding antigens GPIV and GPV, human anti-A specifically bound to these proteins derived from A1-platelets; neither GPIV nor GPV derived from A2-, B- or O-platelets bound anti-A. In a Western blot assay using immunoprecipitated GPIV and GPV as antigens, mAb anti-A immunostained GPIV and GPV precipitated from A1, but not from A2 and O platelets. These results conclusively demonstrate that blood group A antigen is expressed on platelet GPIV and GPV.

Genotyping of the platelet-specific alloantigen HPA-5 (Br(a)/Br(b)) using polymerase chain reaction with sequencespecific primers (PCR-SSP)

A DNA-based one-stage technique, polymerase chain reaction with sequence-specific primers (PCR-SSP) was developed for genotyping of the platelet specific alloantigen HPA-5 (Bra/Brb). Sequence-specific primers, matching the wild type and the point mutation responsible for the HPA-5 (Bra/Brb) phenotype, were constructed. Conjointly a fragment of the gene coding for glycoprotein (GP) IIIa was amplified as an internal control of the enzyme reaction. Using these HPA-5 (Bra/Brb) sequence-specific primers the correct fragment of the GPIa gene was amplified, as evidenced by the PCR product size, the restriction map and by the nucleotide sequence. This assay was applied on 187 Swedish blood donors; 157 individuals were found to have a homozygous HPA-5a (Bra/Brb) genotype and 30 individuals a heterozygous HPA-5a,b (Bra/Brb) genotype. None of the donors was found to display a homozygous HPA-5b (Bra/Brb) genotype. Thus, the (HPA-5b) Bra antigen frequency in this population will be approximately 16.0% with a gene frequency of 8.0%. It is concluded that this assay is an attractive technique for genotyping of the HPA-5 (Bra/Brb) alloantigens on genomic DNA. The technique can replace serological alloantigen typing, especially in cases where platelets and rare human alloantisera are not available.

Long-term results of a prospective randomized comparison of total fundic wrap (Nissen-Rossetti) or semifundoplication (Toupet) for gastro-oesophageal reflux

The importance of the extent of the fundic wrap that encircles the distal oesophagus for the establishment of long-term control of gastro-oesophageal reflux disease (GORD) and for the risk of symptoms after fundoplication was evaluated in a prospective, randomized clinical trial. Of 137 consecutive patients with GORD, 72 were allocated to a semifundoplication (180-200 degrees, Toupet) and 65 to a total fundoplication (360 degrees, Nissen-Rossetti). Dysphagia was more common in the early postoperative period after a total fundic wrap, a difference which disappeared with time. This corresponded to a higher resting tone in the lower oesophageal sphincter area. Seven patients (5 per cent) experienced relapse of GORD during follow-up of more than 3 years. Although no difference in the cumulative relapse rate (5 per cent for Nissen-Rossetti versus 6 per cent for Toupet) was found between the two study groups, the total failure rate was higher (P < 0.05) among patients who had a Nissen-Rossetti procedure because of a procedure-specific complication: intrathoracic herniation of the fundoplication in five patients caused obstructive symptoms without reflux (four had no posterior crural repair). In addition, symptoms in the form of flatulence were more frequently seen after Nissen-Rossetti fundoplication (P < 0.05 at 2 years and P < 0.01 at 3 years). Both Nissen-Rossetti and Toupet fundoplication equally well and durably controlled GORD. Fewer symptoms occurred in those having a semifundoplication, both in the early and late postoperative period.

Blood group A antigen expression in platelets is prominently associated with glycoprotein Ib and IIb. Evidence for an A1/A2 difference

Blood group ABH antigens are associated with platelets as intrinsic determinants and extrinsically adsorbed antigens, and exist both on glycosphingolipids and on glycoproteins (GPs). We now provide direct evidence that the blood group ABH antigens are prominently associated with platelet GPIb and GPIIb. By immunoprecipitation, a murine monoclonal anti-A antibody precipitated surface-biotin-labelled blood group A1 platelet membrane proteins with electrophoretic characteristics identical to those of GPIb/IX and GPIIb/IIIa. By immunoblotting of SDS-PAGE separated blood group A1 platelet proteins the monoclonal anti-A antibody bound to proteins with electrophoretic characteristics identical to those of GPIb and GPIIb. When immunoaffinity purified GPIb/IX and GPIIb/IIIa, derived from blood group O, A1 and A2 platelets, were employed for immunoblotting, GPIb and GPIIb only from A1 platelets bound the monoclonal anti-A antibody. By ELISA, wherein monoclonal antibodies specific for GPIb (APl) and the GPIIb/IIIa complex (AP2) were used to capture and hold antigens from platelet lysate, human anti-A antibodies reacted with these proteins derived from blood group A1 platelets; proteins from blood group A2, O and B platelets showed no reactivity. These results indicate that blood group A antigen is associated with GPIb and GPIIb derived from blood group A1 but not A2 platelets.

DNA sequencing and screening for point mutations in the human Lewis (FUT3) gene enables molecular genotyping of the human Lewis blood group system

The human Lewis gene encodes an alpha(1,3/1,4)-fucosyltransferase responsible for synthesis of the Le(a) and a Le(b) antigens. To define the molecular background for non-functional Lewis genes we have sequenced PCR-amplified DNA fragments from two Le(a-b-) individuals. One was homozygously mutated at nucleotides 202(T --> C) and 314 (C --> T), altering Trp68 to Arg and Thr105 to Met, and the other was homozygously mutated at nucleotides 59 (T --> G) and 1067 (T --> A), altering Leu20 to Arg and Ile356 to Lys. Using PCR we screened for these and additionally one other mutation at nucleotide 508 (G --> A) among 40 Caucasians. Of 15 Le(a-b-) individuals, 7 typed as le59/1067le202/314, 4 as le202/314le202/314 and 1 as le59/1067le59/1067. Of 21 Le(a-b+) and 4 Le(a+b-), 17 typed as LeLe and 7 as Lele202/314. A pedigree study of 8 Lewis-positive individuals showed that the mutations at nucleotides 202 and 314 were located on the same allele.

Increased anti-Gal activity in diabetic patients transplanted with fetal porcine islet cell clusters

The natural anti-Gal antibody seems to create a major obstacle for discordant xenotransplantation in humans. Anti-Gal, which is produced in large amounts in humans (1% of circulating IgG), interacts specifically with the carbohydrate structure Gal alpha 1-3Gal beta 1-4Glc-NAc-R (termed the alpha-galactosyl epitope). This epitope is present in large amounts on porcine cells, as well as on cells of other nonprimate mammals (1 x 10(6) to 35 x 10(6) epitopes/cell). The interaction of anti-Gal with alpha-galactosyl epitopes on the xenograft was found to mediate the immune destruction of discordant xenografts. In the present study, the human immune response to alpha-galactosyl epitopes on xenografts was assessed by measuring changes in anti-Gal titers and affinity in sera of diabetic patients transplanted with fetal porcine islet cell clusters. The activity of this antibody was assessed by a hemagglutination assay with RBC, by ELISA with mouse laminin as a solid-phase antigen, and by equilibrium dialysis with the radiolabeled free haptenic form of the alpha-galactosyl epitope, i.e. [3H]Gal alpha 1-3Gal beta 1-4GlcNAc. All assays revealed a marked increase in anti-Gal activity after transplantation. The increase in anti-Gal titers ranged between 8- and 64-fold. A similar increase was observed in the binding of free alpha-galactosyl epitopes to anti-Gal, as assayed in equilibrium dialysis. Immunoglobulin concentration did not increase after transplantation, suggesting that the observed increase in anti-Gal activity is the result of a specific immune response against alpha-galactosyl epitopes on the xenograft. The elevation in anti-Gal activity was observed in all three immunoglobulin classes and the highest activity was found within the IgG class. Analysis of IgG binding to fixed porcine endothelial cells suggested that most of the observed increased activity against these cells in transplanted patients may be attributed to the elevation in anti-Gal activity.

The platelet-specific alloantigen PlA1 (HPA-1a): a comparison of flow cytometric immunophenotyping and genotyping using polymerase chain reaction and restriction fragment length polymorphism in a Swedish blood donor population

BACKGROUND

There is an increasing interest in the development of rapid and reliable techniques for platelet alloantigen typing.

STUDY DESIGN AND METHODS

By use of standardized flow cytometry and a specific human alloantiserum, 236 Swedish blood donors were immunophenotyped for the platelet-specific alloantigen, PlA1 (HPA-1a).

RESULTS

Ten individuals (4.2%) had low fluorescence intensities and were considered PlA1-negative (HPA-1a-negative); all of them also demonstrated a PlA2/PlA2 (HPA-1b/1b) genotype in a polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) assay of the underlying DNA polymorphism. The remaining population had clear positive fluorescence and was regarded as PlA1-positive (HPA-1a-positive). The fluorescence distribution histogram among PlA1-positive (HPA-1a-positive) individuals was dome-shaped, and those individuals who were homozygous for PlA1 (HPA-1a) could not be distinguished from those who were heterozygous. This finding was further substantiated by PCR-RFLP analysis of the PlA1/PlA2 (HPA-1a/1b) genotype; a heterozygous genotype was found among those having a medium fluorescence intensity as well as among those having a strong fluorescence intensity.

CONCLUSION

Flow cytometry is a valuable tool for large-scale detection of PlA1 (HPA-1a). However, flow cytometry based on only one antiserum cannot distinguish between homozygous and heterozygous carriers of PlA1 (HPA-1a). For zygosity testing and when platelets are difficult to obtain, the PCR-RFLP technique is the assay of choice.

CD4+ and CD8+ T cell expansions using selected TCR V and J gene segments at the onset of giant cell arteritis

OBJECTIVE

To investigate T cell receptor (TCR) V alpha/V beta (and in selected cases, J beta) usage in CD4+ and CD8+ peripheral blood lymphocytes of patients with giant cell arteritis (GCA), before and after treatment, as well as to analyze the HLA types of these patients.

METHODS

Flow cytometry, with 10 anti-TCR V-specific monoclonal antibodies (MAb), was used. To analyze J beta usage by cell populations expressing certain V beta, we used the polymerase chain reaction (PCR) technique, with V beta- and C beta-specific primers, Southern blotting of PCR products, and subsequent hybridization with radiolabeled J beta-specific probes. HLA typing was performed using the microlymphocytotoxicity technique.

RESULTS

Seven of the 9 GCA patients had increased anti-TCR V MAb reactivities (interpreted as T cell expansions), which in many cases, correlated with clinical signs of disease. A strict preference for particular J beta segments was found in 3 of 3 expanded CD4+ T cell populations.

CONCLUSION

T lymphocytes expressing specific antigen receptors are implicated in the pathogenesis of GCA.