Use of non-irradiated blood components in Campath (alemtuzumab)-treated renal transplant patients.

BACKGROUND: The prevention of transfusion-associated graft-versus-host disease (TA-GvHD) through the irradiation of components is key as there is no effective treatment. Universal leucodepletion reduces but may not eliminate TA-GvHD; therefore, irradiation is still recommended. In 2010, Campath (alemtuzumab) was added as an indication for irradiation but was not implemented everywhere. OBJECTIVES: To identify any cases of TA-GvHD in our Campath-conditioned renal transplant patients, who were transfused with non-irradiated components. METHODS: Retrospective study of Campath-conditioned renal transplant patients transfused with non-irradiated components. In those transfused up to 9 months following Campath who survived to 1-year follow-up, TA-GvHD was excluded. For patients not followed-up for a full year, we reviewed medical records for features of TA-GvHD. For patients transfused after 9 months following Campath, survival of at least 3 months following last transfusion excluded TA-GvHD. RESULTS: Six hundred and forty-seven Campath-conditioned renal transplant patients were transfused; 616 were transfused within 9 months following Campath; 601 were alive at 1 year, excluding TA-GvHD. Twelve died and three were not followed-up for a full year, but a review of medical records excluded TA-GvHD. The 31 patients transfused 9 months or longer following Campath were all alive 6 months following the last transfusion, excluding TA-GvHD. CONCLUSIONS: Despite receiving non-irradiated components, none of the 647 Campath-conditioned renal transplant patients developed TA-GvHD. Further reviews to replicate our data could enable change to guidance, at least in UK where components are leucodepleted, as an unnecessary requirement for irradiated components has both clinical delay and cost implications.

Postanastomotic transplant renal artery stenosis: association with de novo class II donor-specific antibodies.

In this study, we analyze the outcomes of transplant renal artery stenosis (TRAS), determine the different anatomical positions of TRAS, and establish cardiovascular and immunological risk factors associated with its development. One hundred thirty-seven of 999 (13.7%) patients had TRAS diagnosed by angiography; 119/137 (86.9%) were treated with angioplasty, of which 113/137 (82.5%) were stented. Allograft survival in the TRAS+ intervention, TRAS+ nonintervention and TRAS- groups was 80.4%, 71.3% and 83.1%, respectively. There was no difference in allograft survival between the TRAS+ intervention and TRAS- groups, p = 0.12; there was a difference in allograft survival between the TRAS- and TRAS+ nonintervention groups, p < 0.001, and between the TRAS+ intervention and TRAS+ nonintervention groups, p = 0.037. TRAS developed at the anastomosis, within a bend/kink or distally. Anastomotic TRAS developed in living donor recipients; postanastomotic TRAS (TRAS-P) developed in diabetic and older patients who received grafts from deceased, older donors. Compared with the TRAS- group, patients with TRAS-P were more likely to have had rejection with arteritis, odds ratio (OR): 4.83 (1.47-15.87), p = 0.0095, and capillaritis, OR: 3.03 (1.10-8.36), p = 0.033. Patients with TRAS-P were more likely to have developed de novo class II DSA compared with TRAS- patients hazard ratio: 4.41 (2.0-9.73), p < 0.001. TRAS is a heterogeneous condition with TRAS-P having both alloimmune and traditional cardiovascular risk factors.

Generic tacrolimus in solid organ transplantation.

The availability of a wide range of immunosuppressive therapies has revolutionized the management of patients who have undergone solid organ transplantation (SOT). However, the cost of immunosuppressive drugs remains high. This situation has led to the development of generic equivalents, which are similar in quality, safety, and efficacy to their approved innovator drugs. There are data available for three generic brands, tacrolimus (Intas), tacrolimus (PharOS), and tacrolimus (Sandoz). Bioequivalence has been demonstrated for generic tacrolimus (Sandoz) within a narrow therapeutic range to its innovator tacrolimus drug (Prograf) in both healthy volunteers and kidney transplant patients. Clinical experience with this generic tacrolimus formulation has also been established in both de novo and conversion patients who have undergone kidney and liver transplantation, as well as in conversion of other SOT patients, including lung and heart recipients.

Microcirculation inflammation associates with outcome in renal transplant patients with de novo donor-specific antibodies.

In renal transplant patients with de novo donor-specific antibodies (dnDSA) we studied the value of microcirculation inflammation (MI; defined by the addition of glomerulitis (g) and peritubular capillaritis (ptc) scores) to assess long-term graft survival in a retrospective cohort study. Out of all transplant patients with standard immunological risk (n = 638), 79 (12.4%) developed dnDSA and 58/79 (73%) had an indication biopsy at or after dnDSA development. Based on the MI score on that indication biopsy patients were categorized, MI0 (n = 26), MI1 + 2 (n = 21) and MI ≥ 3 (n = 11). The MI groups did not differ significantly pretransplantation, whereas posttransplantation higher MI scores developed more anti-HLA class I + II DSA (p = 0.011), showed more TCMR (p < 0.001) and showed a trend to C4d-positive staining (p = 0.059). Four-year graft survival estimates from time of indication biopsy were MI0 96.1%, MI1 + 2 76.1% and MI ≥ 3 17.1%; resulting in a 24-fold increased risk of graft failure in the MI ≥ 3 compared to the MI0 group (p = 0.003; 95% CI [3.0-196.0]). When adjusted for C4d, MI ≥ 3 still had a 21-fold increased risk of graft failure (p = 0.005; 95% CI [2.5-180.0]), while C4d positivity on indication biopsy lost significance. In renal transplant patients with de novo DSA, microcirculation inflammation, defined by g + ptc, associates with graft survival.

Renal allograft recipients fail to increase interferon-γ during invasive fungal diseases.

Invasive fungal diseases are a major cause of death in renal allograft recipients. We previously reported that adjunctive recombinant human interferon-γ therapy has clinical utility for invasive fungal diseases after renal transplantation. We have now developed a rapid peripheral blood-based quantitative real-time PCR assay that enables accurate profiling of cytokine imbalances. Our preliminary studies in renal transplant patients with invasive fungal diseases suggest that they fail to mount an adequate interferon-γ response to the fungal infection. In addition, they have reduced IL-10 and increased TNF-α when compared to stable renal transplant patients. These preliminary cytokine profiling-based observations provide a possible explanation for the therapeutic benefit of adjunctive human interferon-γ therapy in renal allograft recipients with invasive fungal diseases.

Recurrence of complement factor H-related protein 5 nephropathy in a renal transplant.

Complement factor H-related protein 5 (CFHR5) nephropathy is a familial renal disease endemic in Cyprus. It is characterized by persistent microscopic hematuria, synpharyngitic macroscopic hematuria and progressive renal impairment. Isolated glomerular accumulation of complement component 3 (C3) is typical with variable degrees of glomerular inflammation. Affected individuals have a heterozygous internal duplication in the CFHR5 gene, although the mechanism through which this mutation results in renal disease is not understood. Notably, the risk of progressive renal failure in this condition is higher in males than females. We report the first documented case of recurrence of CFHR5 nephropathy in a renal transplant in a 53-year-old Cypriot male. Strikingly, histological changes of CFHR5 nephropathy were evident in the donor kidney 46 days post-transplantation. This unique case demonstrates that renal-derived CFHR5 protein cannot prevent the development of CFHR5 nephropathy.

Outcome of patients with preformed donor-specific antibodies following alemtuzumab induction and tacrolimus monotherapy.

It has been shown that low-level preformed donor-specific antibodies (DSAbs) detected by luminex beads in the setting of a negative CDC and flow cytometry crossmatch (CDC/FCXM) are associated with inferior allograft outcomes. The relevance of preformed DSAbs in patients receiving alemtuzumab induction and tacrolimus monotherapy has not been studied. Four hundred and eighty renal transplant recipients with a negative CDC/FCXM had their pretransplant sera retrospectively screened for DSAbs. 45/480 (9.4%) of patients were found to have preformed DSAbs. Females and patients receiving regrafts were more likely to have a DSAb (p = 0.008 and p < 0.0001, respectively). Patients with DSAbs had inferior allograft survival (p = 0.047), increased incidence of antibody-mediated rejection (p < 0.0001) and inferior allograft function at 6 months posttransplant (p = 0.017). Patients with HLA class I DSAb (alone or in combination with a Class II DSAb) with high mean fluorescence intensities (MFIs) were at highest risk. We conclude that patients with preformed DSAb are at high risk of adverse outcomes when receiving a minimal immunosuppressive regime incorporating alemtuzumab induction. Patients found to have a preformed DSAb despite a negative crossmatch might benefit from augmented immunosuppression.

Exogenous interferon-gamma immunotherapy for invasive fungal infections in kidney transplant patients.

The incidence of invasive fungal infections (IFIs) in nonneutropenic solid organ transplant patients is increasing. We report our clinical experience with the use of interferon-gamma (IFN-gamma) immunotherapy in seven renal transplant patients who developed life threatening, disseminated IFIs refractory to conventional antifungal drug therapy. The infections were all microbiologically and histologically proven. The rapid cure of these disseminated infections with exogenous IFN-gamma injections was not associated with impaired kidney allograft function despite the use of liposomal amphotericin B in all cases. No clinical toxicity from the IFN-gamma immunotherapy was seen and no IFI relapsed during long-term follow-up. Our experience is both uncontrolled and in patients with unpredictable fungal infection-related outcomes. However, compared to standard approaches, the accelerated cure of life threatening, disseminated IFIs with 6 weeks of combination antifungal drug therapy and IFN-gamma immunotherapy saved lives, retained allograft function and led to substantial cost savings in this small patient group.

A mercury-catalyzed, high-yield system for the oxidation of methane to methanol.

A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate ( approximately 43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10(-7) mole per cubic centimeter per second and Hg(II) turnover frequency of 10(-3) per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH(3)HgOSO(3)H, 1. Under the reaction conditions, 1 readily decomposes to CH(3)OSO(3)H and the reduced mercurous species, Hg(2)(2+) The catalytic cycle is completed by the reoxidation of Hg(2)(2+) with H(2)SO(4) to regenerate Hg(II) and byproducts SO(2) and H(2)O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.

Steroid sparing in renal transplantation with tacrolimus and mycophenolate mofetil: three-year results.

Although renal transplantation with a 7-day steroid-sparing regimen, tacrolimus and mycophenolate, is associated with good short-term outcomes, late allograft dysfunction and failure remain concerns. In this study 101 consecutive patients underwent renal transplantation using this immunosuppressive regimen. In addition, anti-CD25 monoclonal antibody was used in 25 high-risk patients (regrafts, two-antigen human leukocyte antigen (HLA)-DR mismatch or sensitized with anti-HLA panel reactivity >30%). After a median follow-up of 39 months (range 29 to 49), overall patient survival is 98%, with two cardiac deaths. Three other graft losses occurred, one each to early venous thrombosis, polyoma viral nephropathy, and late rejection due to noncompliance. Therefore, overall graft survival is 95%. The acute rejection rate at 6 and 12 months was 19% (no rejection occurred between months 6 and 12). Late rejection was uncommon, with only two further episodes beyond 12 months. Mean creatinine at 12 months was 144 micromol/L and mean estimated glomerular filtration rate (GFR) of 55 mL/min. Graft function was stable at 3 years with a mean creatinine of 142 micromol/L and mean estimated GFR 56 mL/min. During the study, five patients developed posttransplant diabetes mellitus (two cases beyond 12 months). Tissue-invasive cytomegalovirus disease and BK viral nephropathy each occurred in three patients, with all episodes in the first 12 months. Mean weight gain is 3.3 kg and mean blood pressure is 135/81 on an average of 1.5 antihypertensive agents. This steroid-avoidance regimen is associated with excellent medium-term patient and graft outcomes and a low incidence of side effects.

Late steroid withdrawal for renal transplant recipients on tacrolimus and MMF is safe.

INTRODUCTION: We conducted a study to assess the safety of staged, late steroid withdrawal in kidney or kidney/pancreas transplant recipients on steroids, tacrolimus, and mycophenolate mofetil (MMF). MATERIALS AND METHODS: We studied 50 patients including 33 recipients of cadaveric kidneys, eight living donor kidneys, and nine kidney-pancreas transplants. The mean time posttransplantation was 5.1 years (range 2.1 to 7.9 years). All patients were induced on prednisolone, tacrolimus, and MMF; steroids were withdrawn over 5 to 6 months. The rate of steroid reduction was altered in the face of typical steroid withdrawal symptoms (limb-girdle arthralgia/myalgia). RESULTS: No rejection episodes occurred during steroid withdrawal. No patient required transplant biopsy for graft dysfunction. Six patients failed steroid withdrawal: five due to arthralgia/myalgia and one due to recurrent pulmonary sarcoidosis. The unexplained rise in serum creatinine following steroid withdrawal described in several other steroid withdrawal studies was not observed in this patient cohort. The mean serum creatinine was 137 micromol/L with deltacreatinine -6.8 micromol/y per year prior to steroid cessation versus 132 micromol/L with deltacreatinine -5.9 micromol/y in the year post-steroid cessation. There were 14 patients with posttransplant diabetes mellitus in this cohort: eight on gliclazide and six on insulin. We observed a reduction in their daily insulin/gliclazide requirements from 52 units to 41 units, and 73 mg to 65 mg, respectively. Two patients became gliclazide-independent at the time of steroid cessation. CONCLUSIONS: Careful steroid withdrawal from a platform of tacrolimus and MMF is safe and not associated with a significant risk of rejection or graft dysfunction.

Tacrolimus monitoring in renal transplantation: a comparison between high-performance liquid chromatography and immunoassay.

It is recommended that specific methods of tacrolimus monitoring rather than immunoassays, which overestimate tacrolimus levels, should be used in transplant recipients. Direct comparison of these techniques, however, has not been conducted in renal transplantation. In this study, 40 renal transplant recipients with tacrolimus monitoring by microparticle enzyme immunoassay (MEIA; target trough level 10 to 15 ng/mL) were compared with 40 patients monitored by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS; target trough level 8 to 13 ng/mL). All patients received anti CD25 antibody induction and mycophenolate mofetil in a steroid-sparing protocol. No differences were seen between MEIA and HPLC-MS groups in patient demographics. All patients were followed for 6 months. Patient survival was 100% in both groups; graft survival was 100% in the MEIA group and 97.5% in the HPLC-MS group. The groups did not differ in the number of dose changes required in the first 6 months or in the number of patients displaying tacrolimus levels within target range at 3 and 6 months. Delayed graft function occurred in 14 patients in the MEIA group and 12 patients in the HPLC-MS group (P = NS). Biopsy-proven acute rejection occurred in four patients in the MEIA group and one patient in the HPLC-MS group (P < .2). No differences were seen for the following parameters at 3 or 6 months: biopsy-proven tacrolimus nephrotoxicity, serum creatinine or estimated creatinine clearance, systolic or diastolic blood pressure, cholesterol, cytomegalovirus disease, posttransplant diabetes, or tremor. This study suggests that renal transplantation with HPLC-MS monitoring of tacrolimus is safe and effective.

Cytokine polymorphisms do not influence acute rejection in renal transplantation under tacrolimus-based immunosuppression.

INTRODUCTION: Acute rejection remains an important cause of graft loss after renal transplantation. It has been suggested that cytokine genotyping may play a predictive role in identifying individuals who are at higher risk of acute rejection with a view to individualizing their immunosuppression. The aim of this study was to investigate any possible associations between acute rejection and certain cytokine polymorphisms. METHODS: We genotyped 91 cadaveric renal transplant recipients on tacrolimus-based immunosuppression and 84 of their donors. The cytokine polymorphisms studied were the following: tumor necrosis factor (TNF)-alpha-1032 T/C, TNF-alpha-865 C/A, TNF-alpha-859 G/A, interleukin (IL)1-R1-970 C/T, IL-10 haplotype [-1082, -819, -592], and IL-6-174 C/G. RESULTS: We found no association between any polymorphism and the incidence of acute rejection. This was true for both the recipient and donor population. CONCLUSION: Cytokine polymorphisms did not influence acute rejection in our study. We conclude that in the modern era of immunosuppression cytokine genotyping is not a significant predictor of acute rejection in renal transplantation.

A Systematic Review of Outcomes Following Percutaneous Transluminal Angioplasty and Stenting in the Treatment of Transplant Renal Artery Stenosis.

PURPOSE: To evaluate outcomes following treatment of transplant renal artery stenosis by percutaneous transluminal angioplasty and stent insertion. MATERIALS AND METHODS: A literature search was performed using Pubmed, MEDLINE, Embase, Wiley Interscience and the Cochrane Library databases. Outcome measures were glomerular filtration rate, creatinine, blood pressure and number of antihypertensive medications. Technical and clinical success, patency and complication rates were also analysed. RESULTS: Thirty-two studies met the inclusion criteria, involving a total of 884 interventions including PTA, stenting, or combinations of both. Clinical success rates were in the range 65.5-94%. The majority of studies reported technical success rates higher than 90%. Patency rates were in the range of 42-100%. However, the definition and diagnostic criteria for TRAS varied widely between studies. Also, marked heterogeneity was observed in the reporting of outcome measures with no consensus in outcome criteria or follow up schedule. CONCLUSION: Outcomes following PTA and stenting for the treatment of TRAS have been shown to be favourable. However, there is a distinct lack of well designed studies assessing outcomes following intervention. Outcome reporting may be improved by the introduction of standardised outcome measures with reporting of outcomes into a multi-centre registry.

Adriamycin analogues. Preparation and biological evaluation of some N-(trifluoroacetyl)-14-O-[(N-acetylamino)acyl]adriamycin derivatives.

In connection with structure-activity studies related to the novel DNA-nonbinding adriamycin analogues N-(trifluoroacetyl)adriamycin 14-valerate (AD 32) and N-(trifluoroacetyl)adriamycin 14-O-hemiadipate (AD 143), we have now prepared a series of N-(trifluoroacetyl)adriamycin derivatives with N-acylamino acid esters at the 14-carbinol position. Target compounds were made by reaction of N-(trifluoroacetyl)-14-iododaunorubicin with the sodium salts of N-acylamino acids generally in dimethylformamide-ethylene glycol solvent. Products were evaluated for in vitro growth-inhibitory activity and, to a limited extent, in vivo antitumor activity in the murine P388 leukemia system. ID50 values for the target compounds vs. cultured CCRF-CEM cells were generally in the same range as those for the above-mentioned DNA nonbinding adriamycin analogues. Of the four compounds tested for in vivo activity, although none was as effective as N-(trifluoroacetyl)adriamycin 14-valerate, all showed significant activity in the P388 assay system, with three of the compounds, at the doses used, being essentially equiactive with an optimal dose of adriamycin. Studies on the rate of esterase-mediated deacylation of the products, in a defined system containing unfractionated mouse serum as the source of enzyme, showed no relationship between the in vitro and in vivo activities of these compounds and the relative ease at which the side-chain ester substituents were hydrolyzed.

Immunoglobulin (Gm) allotype frequencies in idiopathic membranous nephropathy and minimal change nephropathy.

40 Caucasoid patients with idiopathic membranous nephropathy (IMN) and 49 Caucasoid patients with minimal change nephropathy (MCN) were immunoglobulin allotyped for the Gm markers G1m (1, 2, 3) and G3m (5, 11, 21). Compared with normal controls the IMN group had a significantly decreased incidence of the G1m (3); G3m (5, 11) phenotype (P = less than 0.005). This decrease was accompanied by concommitant increase in both the G1m (1, 3); G3m (5, 11, 21) and the G1m (1, 2, 3); G3m (5, 11, 21) phenotypes. The result was most pronounced in IMN patients with deteriorating renal function. In contrast no significant differences were observed between the Gm phenotype frequencies of the MCN patients and controls.

IgG2 anti-Galalpha1-3Gal does not induce porcine aortic endothelial cell accommodation in vitro.

BACKGROUND: Xenografts that have been protected from hyperacute rejection (HAR) are termed accommodated if they are not then rejected despite the presence of xenoantibody. It has been proposed that IgG may confer resistance to complement dependent cytotoxicity (CDC), a conventional in vitro marker of accommodation. We hypothesized that noncytotoxic IgG2 anti-Galalpha1-3Gal was responsible for this effect. METHODS AND RESULTS: We purified IgG anti-Galalpha1-3Gal from pooled human normal immunoglobulin and three sera, by elution from protein G and Galalpha1-3Gal-R immunoadsorbents. The eluates were IgM free and > or =95% IgG2. They bound to Galalpha1-3Gal, porcine aortic endothelial cells (PAEC) and lymphocytes. It was not possible to block IgM binding to PAEC or lymphocytes using IgG anti-Galalpha1-3Gal (200 microg/ml). The eluates were noncytotoxic in micro-CDC assays. To investigate accommodation, PAEC were cultured with subsaturating doses of the four IgG eluates for up to 144 hr. Resistance of nontrypsinized PAEC to CDC by human serum was measured in a cell viability assay. PAEC were not rendered resistant to CDC in any of the experiments. To investigate the possibility that accommodation might be induced by non-Galalpha1-3Gal IgG, the experiments were repeated using HNIg, again with no protection demonstrated. CONCLUSIONS: Using primary PAEC monolayers, we were unable to induce resistance to CDC with human normal immunoglobulin and its IgG2 anti-Gabeta1-3Gal subset. This contradicts previous experiments using trypsinized, immortalized cells. Although resistance to CDC is not an ideal marker of accommodation, the detrimental effects of IgG make it unlikely that it will become a useful clinical means of inducing accommodation.

Tc-99m DTPA scans in renal allograft rejection and cyclosporine nephrotoxicity.

Renal allograft dysfunction arising from rejection or cyclosporine (CsA) nephrotoxicity can currently only be distinguished reliably by allograft biopsy. We have assessed Technetium (Tc)-99m diethylamine pentacetic acid (DTPA) scanning in 30 CsA-treated patients with allograft dysfunction. Scintigrams were performed during 20 biopsy-proved episodes of rejection and during 14 episodes of CsA nephrotoxicity. These results were compared with the scintigrams of 15 allografts showing stable function. Quantitative indices expressing allograft perfusion (flow index) and function (uptake index) derived from the DTPA scintigrams showed no significant differences between the groups of patients with rejection, CsA nephrotoxicity, or stable or improving function. Similarly, the flow and uptake indices of individual allografts obtained during periods of stable or improving function and then during episodes of dysfunction due to rejection or CsA nephrotoxicity did not significantly change. We conclude that Tc-99m DTPA scintigrams are of limited value in the management of allograft dysfunction in patients immunosuppressed with CsA.

Demonstration of IgM antibodies of high affinity within the anti-Galalpha1-3Gal antibody repertoire.

BACKGROUND: Human anti-Galalpha1-3Gal IgG and IgM xenoantibodies can distinguish between very similar epitopes with a high degree of selectivity. METHODS: Anti-Galalpha1-3Gal antibodies were affinity isolated using two separate Galalpha1-3Gal-based immunoadsorbents, Galalpha1-3Gal itself and Galalpha1-3Galbeta1-4Glc. IgG and IgM were separated using a protein G column. Antibody purity was achieved by serial adsorption/elutions from the columns. By this means, different antibody fractions were prepared that contained either IgG or IgM, reactive with either Galalpha1-3Gal, Galalpha1-3Galbeta1-4Glc, or both. The dissociation equilibrium constants (Kd) of these antibodies were then measured using an IAsys biosensor. RESULTS AND CONCLUSIONS: Sera from two individuals were used and Kd values for one IgG (fraction 1A) and two IgM (fractions 1B and 2A) fractions were obtained. The Kd for the IgG was 4.85 x 10(-7) M (fraction 1A). For IgM, the Kd values were higher at 7.8x10(-10) M (fraction 1B) and 1.07x10(-10) M (fraction 2A). Natural anti-pig antibodies include high affinity IgM that continue to be produced without class switch. The B cell mechanism behind this is not known. It may be possible to exploit this mechanism in future xenotransplantation strategies.

Inhibition of the pig to human xenograft reaction, using soluble Gal alpha 1-3Gal and Gal alpha 1-3Gal beta 1-4GlcNAc.

Natural anti-carbohydrate antibodies are central to hyperacute rejection in ABO-incompatible allotransplantation and in discordant xenotransplantation. ABO-incompatible rejection has been inhibited successfully using intravenous soluble carbohydrates as antibody inhibitors. The approach has been less successful previously in pig to primate xenotransplantation, where the necessary concentrations of a partial inhibitor (Gal alpha 1-6Glc) proved highly toxic. In this study, we have identified more effective inhibitors of the dominant human anti-pig antibodies that bind to the pentasaccharide Gal alpha 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-. The inhibitors are the terminal disaccharide (Gal alpha 1-3Gal) and terminal trisaccharide (Gal alpha 1-3Gal beta 1-4GlcNAc) of the target pentasaccharide. Twelve sera (3 from each ABO blood group) were tested in 3 different assays: lymphocytotoxic, lymphocyte flow cytometry, and solid-phase antigen ELISA. Fifty percent to 75% inhibition of human IgG and IgM was achieved using the disaccharide and trisaccharide inhibitors in the range of 10-50 mM. Disaccharide (70 mM) was used to inhibit hyperacute thrombosis in pig kidneys perfused for 40 min with heparinized human AB whole blood. The disaccharide completely inhibited red cell occlusion of glomerular but not of intertubular capillaries, although there was residual platelet thrombus in glomeruli. Disaccharide and trisaccharide can, therefore, be used in concentrations shown for other carbohydrate inhibitors to be nontoxic, for inhibition of hyperacute pig-to-human xenograft rejection. The inhibition is incomplete, however, and other antigen specificities and other rejection mechanisms are likely to be involved.