Gastrointestinal hypomotility with loss of enteric nicotinic acetylcholine receptors: active immunization model in mice

BACKGROUND

Autoimmune gastrointestinal dysmotility (AGID) is a limited form of dysautonomia. The only proven effector to date is IgG specific for ganglionic nicotinic-acetylcholine receptors containing α3 subunits [α3*- nicotinic acetylcholine receptor (nAChR)]. Rabbits immunized with recombinant α3-polypeptide produce α3*-nAChR autoantibodies, and profound AGID ensues. Human and rabbit α3*-nAChR-specific-IgGs induce transient hypomotility when injected into mice. Here, we describe success and problems encountered inducing gastrointestinal hypomotility in mice by active immunization.

METHODS

We repeatedly injected young adult mice of seven different strains susceptible to autoimmunity (spontaneous diabetes or neural antigen immunization-induced myasthenia gravis or encephalomyelitis) with: (i) α3-polypeptide, intradermally or (ii) live α3*-nAChR-expressing xenogeneic cells, intraperitoneally. We measured serum α3*-nAChR-IgG twice monthly, and terminally assessed blue dye gastrointestinal transit, total small intestinal α3*-nAChR content (radiochemically) and myenteric plexus neuron numbers (immunohistochemically, ileal-jejunal whole-mount preparations).

KEY RESULTS

Standard cutaneous inoculation with α3-polypeptide was minimally immunogenic, regardless of dose. Intraperitoneally injected live cells were potently immunogenic. Self-reactive α3*-nAChR-IgG was induced only by rodent immunogen; small intestinal transit slowing and enteric α3*-nAChR loss required high serum levels. Ganglionic neurons were not lost.

CONCLUSIONS & INFERENCES

Autoimmune gastrointestinal dysmotility is inducible in mice by active immunization. Accompanying enteric α3*-nAChR reduction without neuronal death is consistent with an IgG-mediated rather than T cell-mediated pathogenesis, as is improvement of symptoms in patients receiving antibody-depleting therapies.

Astrocytic autoantibody of neuromyelitis optica (NMO-IgG) binds to aquaporin-4 extracellular loops, monomers, tetramers and high order arrays

The principal central nervous system (CNS) water channel, aquaporin-4 (AQP4), is confined to astrocytic and ependymal membranes and is the target of a pathogenic autoantibody, neuromyelitis optica (NMO)-IgG. This disease-specific autoantibody unifies a spectrum of relapsing CNS autoimmune inflammatory disorders of which NMO exemplifies the classic phenotype. Multiple sclerosis and other immune-mediated demyelinating disorders of the CNS lack a distinctive biomarker. Two AQP4 isoforms, M1 and M23, exist as homotetrameric and heterotetrameric intramembranous particles (IMPs). Orthogonal arrays of predominantly M23 particles (OAPs) are an ultrastructural characteristic of astrocytic membranes. We used high-titered serum from 32 AQP4-IgG-seropositive patients and 85 controls to investigate the nature and molecular location of AQP4 epitopes that bind NMO-IgG, and the influence of supramolecular structure. NMO-IgG bound to denatured AQP4 monomers (68% of cases), to native tetramers and high order arrays (90% of cases), and to AQP4 in live cell membranes (100% of cases). Disease-specific epitopes reside in extracellular loop C more than in loops A or E. IgG binding to intracellular epitopes lacks disease specificity. These observations predict greater disease sensitivity and specificity for tissue-based and cell-based serological assays employing "native" AQP4 than assays employing denatured AQP4 and fragments. NMO-IgG binds most avidly to plasma membrane surface AQP4 epitopes formed by loop interactions within tetramers and by intermolecular interactions within high order structures. The relative abundance and localization of AQP4 high order arrays in distinct CNS regions may explain the variability in clinical phenotype of NMO spectrum disorders.

Academic careers and lifestyle characteristics of 171 transplant surgeons in the ASTS

This manuscript reports the demographics, education and training, professional activities and lifestyle characteristics of 171 members of the American Society of Transplant Surgeons (ASTS). ASTS members were sent a comprehensive survey by electronic mail. There were 171 respondents who were 49 ± 8 years of age and predominantly Caucasian males. Female transplant surgeons comprised 10% of respondents. ASTS respondents underwent 15.6 ± 1.0 years of education and training (including college, medical school, residency and transplantation fellowship) and had practiced for 14.7 ± 9.2 years. Clinical practice included kidney, pancreas and liver organ transplantation, living donor surgery, organ procurement, vascular access procedures and general surgery. Transplant surgeons also devote a significant amount of time to nonsurgical patient care, research, education and administration. Transplant surgeons, both male and female, reported working approximately 70 h/week and a median of 195 operative cases per year. The anticipated retirement age for men was 64.6 ± 8.6 and for women was 62.2 ± 4.2 years. This is the largest study to date assessing professional and lifestyle characteristics of abdominal transplant surgeons.

Prediction of neuromyelitis optica attack severity by quantitation of complement-mediated injury to aquaporin-4-expressing cells

BACKGROUND

Recent reports support a pathogenic role in neuromyelitis optica (NMO) for the aquaporin-4 (AQP4)-specific autoantibody (NMO-IgG). Neuromyelitis optica is an inflammatory demyelinating central nervous system disease, usually relapsing, that causes variable degrees of attack-related disability. The NMO-IgG binds in vitro to the extracellular domain of AQP4, activates complement, and causes astrocyte lesioning.

OBJECTIVE

To compare the prognostic utility of NMO-IgG titer and quantitative measures of complement-mediated injury to AQP4-expressing cells in NMO attacks.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective clinical-serological correlative study at Mayo Clinic's Neuroimmunology Laboratory was undertaken. Over an 18-month period, we identified NMO-IgG-seropositive patients in whom sufficient serum and adequate clinical information pertaining to NMO attacks (6 severe, 6 mild) were available to analyze clinical-serological correlations. Sera from 9 patients with multiple sclerosis and 9 healthy subjects (all NMO-IgG seronegative) served as controls. Complement activation was measured by quantifying the number of green fluorescent protein-AQP4-transfected HEK 293 cells permeable to the viability dye propidium iodide after exposure to patient serum and active complement.

MAIN OUTCOME MEASURES

Attack severity (mild or severe), percentage of AQP4-transfected cells lesioned, and NMO-IgG titer.

RESULTS

The median percentage of AQP4-transfected cells lesioned by complement in the presence of serum from patients with NMO was 14% for patients with mild attacks and 54% for patients with severe attacks (P = .005). Median complement activation values for sera from healthy subjects and patients with multiple sclerosis were 8% and 12%, respectively. Patients with mild NMO attacks and patients with severe NMO attacks did not differ significantly with respect to NMO-IgG titer (P = .089).

CONCLUSIONS

A laboratory measure of complement-mediated cell injury may serve as a prognostic biomarker in NMO. Larger prospective studies are required to validate this observation.

Aquaporin-4-binding autoantibodies in patients with neuromyelitis optica impair glutamate transport by down-regulating EAAT2

Neuromyelitis optica (NMO)-immunoglobulin G (IgG) is a clinically validated serum biomarker that distinguishes relapsing central nervous system (CNS) inflammatory demyelinating disorders related to NMO from multiple sclerosis. This autoantibody targets astrocytic aquaporin-4 (AQP4) water channels. Clinical, radiological, and immunopathological data suggest that NMO-IgG might be pathogenic. Characteristic CNS lesions exhibit selective depletion of AQP4, with and without associated myelin loss; focal vasculocentric deposits of IgG, IgM, and complement; prominent edema; and inflammation. The effect of NMO-IgG on astrocytes has not been studied. In this study, we demonstrate that exposure to NMO patient serum and active complement compromises the membrane integrity of CNS-derived astrocytes. Without complement, astrocytic membranes remain intact, but AQP4 is endocytosed with concomitant loss of Na⁺-dependent glutamate transport and loss of the excitatory amino acid transporter 2 (EAAT2) . Our data suggest that EAAT2 and AQP4 exist in astrocytic membranes as a macromolecular complex. Transport-competent EAAT2 protein is up-regulated in differentiating astrocyte progenitors and in nonneural cells expressing AQP4 transgenically. Marked reduction of EAAT2 in AQP4-deficient regions of NMO patient spinal cord lesions supports our immunocytochemical and immunoprecipitation data. Thus, binding of NMO-IgG to astrocytic AQP4 initiates several potentially neuropathogenic mechanisms: complement activation, AQP4 and EAAT2 down-regulation, and disruption of glutamate homeostasis.

CNS aquaporin-4 autoimmunity in children

BACKGROUND

In adult patients, autoantibodies targeting the water channel aquaporin-4 (AQP4) are a biomarker for a spectrum of CNS inflammatory demyelinating disorders with predilection for optic nerves and spinal cord (neuromyelitis optica [NMO]). Here we describe the neurologic, serologic, and radiographic findings associated with CNS AQP4 autoimmunity in childhood.

METHODS

A total of 88 consecutive seropositive children were identified through service evaluation for NMO-IgG. Sera of 75 were tested for coexisting autoantibodies. Clinical information was available for 58.

RESULTS

Forty-two patients (73%) were non-Caucasian, and 20 (34%) had African ethnicity. Median age at symptom onset was 12 years (range 4-18). Fifty-seven (98%) had attacks of either optic neuritis (n = 48; 83%) or transverse myelitis (n = 45; 78%), or both. Twenty-six (45%) had episodic cerebral symptoms (encephalopathy, ophthalmoparesis, ataxia, seizures, intractable vomiting, or hiccups). Thirty-eight (68%) had brain MRI abnormalities, predominantly involving periventricular areas (in descending order of frequency): the medulla, supratentorial and infratentorial white matter, midbrain, cerebellum, thalamus, and hypothalamus. Additional autoantibodies were detected in 57 of 75 patients (76%), and 16 of 38 (42%) had a coexisting autoimmune disorder recorded (systemic lupus erythematosus, Sjögren syndrome, juvenile rheumatoid arthritis, Graves disease). Attacks were recurrent in 54 patients (93%; median follow-up, 12 months). Forty-three of 48 patients (90%) had residual disability: 26 (54%) visual impairment and 21 (44%) motor deficits (median Expanded Disability Status Scale 4.0 at 12 months).

CONCLUSIONS

Aquaporin-4 autoimmunity is a distinctive recurrent and widespread inflammatory CNS disease in children.

Pathogenic potential of IgG binding to water channel extracellular domain in neuromyelitis optica

BACKGROUND

Autoantibody specific for the aquaporin-4 astrocytic water channel is restricted to serum and CSF of patients with neuromyelitis optica (NMO) and related CNS inflammatory demyelinating disorders (relapsing optic neuritis and longitudinally extensive transverse myelitis). NMO-typical lesions are distinct from MS-typical lesions. Aquaporin-4 is lost selectively at vasculocentric sites of edema/inflammation coinciding with focal deposits of immunoglobulins (Ig) G, M, and terminal complement products, with and without myelin loss. Evidence for antigen-specific autoantibody pathogenicity is lacking.

METHODS

We used confocal microscopy and flow cytometry to evaluate the selectivity and immunopathological consequences of Ig binding to surface epitopes of living target cells expressing aquaporin-4 fused at its cytoplasmic N-terminus with GFP. We tested serum, IgG-enriched and IgG-depleted serum fractions, and CSF from patients with NMO, neurologic control patients, and healthy subjects. We also analyzed aquaporin-4 immunoreactivity in myelinated adult mouse optic nerves and spinal cord, and plasma cell Ig isotypes in archived brain tissue from an NMO patient.

RESULTS

Serum IgG from patients with NMO binds to the extracellular domain of aquaporin-4; it is predominantly IgG(1), and it initiates two potentially competing outcomes, aquaporin-4 endocytosis/degradation and complement activation. Serum and CSF lack aquaporin-4-specific IgM, and plasma cells in CNS lesions of NMO contain only IgG. Paranodal astrocytic endfeet highly express aquaporin-4.

CONCLUSIONS

NMO patients' serum IgG has a selective pathologic effect on cell membranes expressing aquaporin-4. IgG targeting astrocytic processes around nodes of Ranvier could initiate demyelination.

Liver and intestine transplantation in the United States, 1996-2005

The number of liver transplants performed yearly has slowly and steadily increased over the last 10 years, reaching 6441 procedures in 2005. The number of living donor liver transplants performed rose steadily from 1996 to 2001, when it peaked at 519; since 2003 there have been approximately 320 such procedures performed each year. The continual increase in the size of the waiting list for a liver transplant, which peaked in 2001 at 14 897 patients, was interrupted in 2002 by the implementation of the allocation system based on the model for end-stage liver disease and pediatric end-stage liver disease (MELD/PELD). Activity in all areas of intestinal transplantation continues to increase. One-year patient and graft survival following intestine-alone transplantation now seem to be superior to outcomes following liver-intestine transplantation. Other topics covered here include the recent 'Share 15' component of the MELD allocation system; liver transplantation following donation after cardiac death; simultaneous liver-kidney transplantation and waiting list and post-transplant outcomes for both liver and intestine transplantation, broken out by a variety of clinical and demographic factors.

Simple purification methods for an alphagalactose-specific antibody from chicken eggs

For many applications avian antibody from egg yolk (IgY) offers advantages over the well-known mammalian antibodies. Different experimental techniques for the purification of IgY from chickens immunized with an alphagalactose-containing antigen (alphaGal-trisaccharide) were compared. These included ammonium sulfate precipitation, filtration with diatomaceous earth, treatment with deoxycholate, and thiophilic and affinity chromatography. Samples were tested for overall purity, protein and lipid content, and specific activity. Evaluated on the basis of these results and the simplicity of the process, the favored purification method is ammonium sulfate precipitation of diluted egg yolk directly followed by affinity chromatography. The high lipid content of IgY preparations is greatly reduced by either thiophilic or affinity chromatography. Affinity purification of ammonium sulfate precipitated material resulted in anti-alphaGal-trisaccharide IgY preparations with approximately 1% of the original protein content but approximately 100-fold higher specific activity for the alphaGal-trisaccharide epitope.

Simple purification methods for an alphagalactose-specific antibody from chicken eggs

For many applications avian antibody from egg yolk (IgY) offers advantages over the well-known mammalian antibodies. Different experimental techniques for the purification of IgY from chickens immunized with an alphagalactose-containing antigen (alphaGal-trisaccharide) were compared. These included ammonium sulfate precipitation, filtration with diatomaceous earth, treatment with deoxycholate, and thiophilic and affinity chromatography. Samples were tested for overall purity, protein and lipid content, and specific activity. Evaluated on the basis of these results and the simplicity of the process, the favored purification method is ammonium sulfate precipitation of diluted egg yolk directly followed by affinity chromatography. The high lipid content of IgY preparations is greatly reduced by either thiophilic or affinity chromatography. Affinity purification of ammonium sulfate precipitated material resulted in anti-alphaGal-trisaccharide IgY preparations with approximately 1% of the original protein content but approximately 100-fold higher specific activity for the alphaGal-trisaccharide epitope.

Identification and Characterization of a DNase Hypersensitive Region of the Human Tyrosinase Gene

Mutations of the tyrosinase gene produce oculocutaneous albinism type 1 (OCA1). Most affected individuals are compound heterozygotes with different maternal and paternal mutations, but a substantial number of presumed tyrosinase alleles in these individuals have no identifiable mutation in the coding or proximal promoter region of the gene. This suggests that mutations in other regions of the gene, such as regulatory regions that are removed from the direct proximity of the coding sequence, may account for these currently unidentifiable mutations. The mouse tyrosinase gene has a distal enhancer or locus control region (LCR) that provides position-independent stimulation of gene expression, and a homologous regulatory region (HR) of the human gene could be the site of some of these mutations. We report a region 9 kb upstream of the human tyrosinase transcriptional start site that may be involved in regulation of this gene. Analysis of this region shows DNase I hypersensitivity in a cell lineage-specific pattern, a pattern indicative of regulatory regions of a gene. This region also has significant enhancer function when reporter vectors containing it are transfected into either human or mouse melanocyte cell lines, and elimination of specific sequences with homology to the mouse core enhancer in this region extinguishes the enhancer function. We believe that this region of homology contains sequences critical in the regulation of the human tyrosinase gene and is a candidate for the location of OCA1 mutations.

Tyrosinase gene mutations in oculocutaneous albinism�1 (OCA1): definition of the phenotype

Oculocutaneous albinism (OCA) is a common human genetic condition resulting from mutations in at least twelve different genes. OCA1 results from mutations of the tyrosinase gene and presents with the life-long absence of melanin pigment after birth (OCA1A) or with the development of minimal-to-moderate amounts of cutaneous and ocular pigment (OCA1B). Other types of OCA have variable amounts of cutaneous and ocular pigment. We hypothesized that white hair at birth indicates OCA1 and tested this in a sample of 120 probands with OCA and white hair at birth. We found that 102 (85%) of the probands had OCA1 with one or two identifiable tyrosinase gene mutations, with 169 (83%) of the 204 OCA1 tyrosinase gene alleles having identifiable mutations and 35 (17%) having no identifiable change in the coding, splice junction, or proximal promoter regions of the gene. The inability to identify the mutation was more common with OCA1B (24/35, 69%) than with OCA1A (11/35, 31%) alleles. Seven probands with no tyrosinase gene mutations were found to have OCA2 with one or two P gene mutations, and in eleven, no mutations were detected in either gene. We conclude that (1) the presence of white hair at birth is a useful clinical tool suggesting OCA1 in a child or adult with OCA, although OCA2 may also have this presentation; (2) the molecular analysis of the tyrosinase and P genes are necessary for precise diagnosis; and (3) the presence of alleles without identifiable mutations of the tyrosinase gene, particularly in OCA1B, suggests that more complex mutation mechanisms of this gene are common in OCA.

MC1R mutations modify the classic phenotype of oculocutaneous albinism type 2 (OCA2)

The heterogeneous group of disorders known as oculocutaneous albinism (OCA) shares cutaneous and ocular hypopigmentation associated with common developmental abnormalities of the eye. Mutations of at least 11 loci produce this phenotype. The majority of affected individuals develop some cutaneous melanin; this is predominantly seen as yellow/blond hair, whereas fewer have brown hair. The OCA phenotype is dependent on the constitutional pigmentation background of the family, with more OCA pigmentation found in families with darker constitutional pigmentation, which indicates that other genes may modify the OCA phenotype. Sequence variation in the melanocortin-1 receptor (MC1R) gene is associated with red hair in the normal population, but red hair is unusual in OCA. We identified eight probands with OCA who had red hair at birth. Mutations in the P gene were responsible for classic phenotype of oculocutaneous albinism type 2 (OCA2) in all eight, and mutations in the MC1R gene were responsible for the red (rather than yellow/blond) hair in the six of eight who continued to have red hair after birth. This is the first demonstration of a gene modifying the OCA phenotype in humans.

Oculocutaneous albinism type 1: the last 100 years

Research on human albinism has been central to many of the major discoveries in human genetics. These include the first evidence that Mendel's rules of genetic segregation apply to humans, first published in 1903. Contrary to initial thought that albinism is caused by mutations in a single gene, we now know that the genetics of albinism are complex. The complexity of albinism was hinted at, in early publications, but has only recently been fully appreciated with the advent of molecular techniques. Currently, 12 different genes have been identified, that when mutated, result in a different type of albinism. Oculocutaneous albinism type 1 (OCA1), resulting from mutations of the tyrosinase gene, is genetically and biochemically the best understood type of albinism. Though much of the research in albinism has involved OCA1, there are many unanswered questions about OCA1 and albinism, in general. The next 100 yr should still provide many surprises as did the first 100 yr.

Risk factors and impact of cytomegalovirus disease in simultaneous pancreas-kidney transplantation

BACKGROUND

The relevance of cytomegalovirus (CMV) in simultaneous pancreas kidney (SPK) transplant recipients in the modern era of immunosuppression and antiviral therapeutics is largely unquantified. We sought to determine the risk factors of CMV disease and its impact on SPK transplant outcomes in recipients all receiving a consistent regime of maintenance immunosuppression and CMV prophylaxis.

METHODS

This is a retrospective, single center study of 100 consecutive SPK transplant recipients. All received maintenance immunosuppression with mycophenolate mofetil, tacrolimus, and prednisone. CMV prophylaxis consisted of a short course of parenteral gancyclovir followed by oral gancyclovir. Recipients at high-risk (D+/R-) for CMV also received CMV hyperimmune globulin. Multivariate analysis of risk factors for CMV disease and risk factors for adverse outcomes in SPK transplantation were determined. The effect of duration of prophylaxis on timing and severity of CMV disease in high-risk (D+/R-) SPK transplant recipients was also evaluated.

RESULTS

The actual 1-year rate of CMV disease was 17.0% (12.0% noninvasive, 5.0% tissue invasive); and according to donor and recipient CMV serological status was: D-/R+: 0%; D-/R-: 2.8%; D+/R+: 25.6%; and D+/R-: 40.6%. Multivariate analysis showed transplantation of organs from a donor with positive CMV serology to be predictive of CMV disease with a relative risk of 63.37 (P=0.0052). In the high-risk (D+/R-) subgroup, the duration of prophylactic therapy delayed onset of CMV disease, but had minimal effect on severity. Invasive CMV disease was an independent predictor of mortality but did not decrease kidney or pancreas allograft survival.

CONCLUSIONS

Outcomes of SPK transplantation have improved in the current era of modern immunosuppression, yet CMV remains an important pathogen. The serological status of the organ donor and the duration of CMV prophylaxis are predictive of who and when CMV disease may occur. Nevertheless, new strategies that reduce risk and severity of CMV disease are still needed.

Alternative splicing of the tyrosinase gene transcript in normal human melanocytes and lymphocytes

We have identified and isolated ectopically expressed tyrosinase transcripts in normal human melanocytes and lymphocytes and in a human melanoma (MNT-1) cell line to establish a baseline for the expression pattern of this gene in normal tissue. Tyrosinase mRNA from human lymphoblastoid cell lines was reverse transcribed and amplified using specific "nested" primers. This amplification yielded eight identifiable transcripts; five that resulted from alternative splicing patterns arising from the utilization of normal and alternative splice sequences. Identical splicing patterns were found in transcripts from human primary melanocytes in culture and a melanoma cell line, indicating that lymphoblastoid cell lines provide an accurate reflection of transcript processing in melanocytes. Similar splicing patterns have also been found with murine melanocyte tyrosinase transcripts. Our results demonstrate that alternative splicing of human tyrosinase gene transcript produces a number of predictable and identifiable transcripts, and that human lymphoblastoid cell lines provide a source of ectopically expressed transcripts that can be used to study the biology of tyrosinase gene expression in humans.

Pancreas transplantation at Northwestern University

The collective advances made by many groups have significantly improved the results of pancreas transplantation. We have focused on the development of safe and effective immunotherapy, including a new protocol of rapid withdrawal of corticosteroids, the analysis of surgical technique of pancreas exocrine drainage on outcome and the role of SPK transplantation in patients with significant cardiovascular disease. We have found that multimodal immunotherapy including induction with tacrolimus-based maintenance combined with either MMF or sirolimus, with or without corticosteroids, resulted in excellent patient and graft survival rates with low rates of rejection. In this setting, enteric drainage was preferable to bladder drainage because of a lower rate of complications leading to hospital readmissions. Careful pretransplant screening for cardiovascular disease should be routinely performed for all SPK candidates. If successful coronary revascularization can be achieved, these patients can safely undergo SPK transplantation, with 5-year outcomes similar to those for recipients without coronary disease. Finally, we have observed that pancreas transplantation has an important ameliorating effect on hypertension that is independent of the method of pancreas exocrine drainage.

The role of intestinal transplantation in the management of intestinal failure

Significantly reduced morbidity and mortality is needed before intestinal transplantation will be applicable in most patients with intestinal failure who are on long-term total parenteral nutrition (TPN). However, transplantation does play a role if TPN fails, with failure defined by Medicare as liver failure, frequent line sepsis, major central vein thrombosis, or recurrent dehydration. Of these complications, the relationship between liver failure and subsequent death in high-risk subgroups of long-term TPN patients has been shown clearly. Patients with less than 100 cm of postduodenal small bowel, an end-jejunostomy, no ileocecal valve or cecum, or persistently elevated liver function levels are at high risk for end-stage liver disease (ESLD). Early referral to experienced centers is suggested in these circumstances. High-risk patients may also take part in clinical trials of promising therapies to increase intestinal adaptation and prevent liver failure. Living donors should be considered for transplant candidates to minimize waiting time and optimize HLA matching. ESLD patients need a liver-intestine transplant. Because their waiting-list mortality is very high, their status on the liver waiting list should be elevated if possible. High incidence of early death from sepsis is reported after intestinal transplant, even at experienced centers. Aggressive measures should be taken if uncontrolled sepsis occurs, including discontinuing immunosuppression and removing the graft. Further research is needed in intestinal immunology and in development of strategies to decrease the need for aggressive immunosuppression in these transplant recipients. The ultimate role of intestinal transplantation will be determined by its capacity to show superiority, both in effectiveness and safety, to long-term TPN.

Distribution of, and immune response to, chicken anti-alpha Gal immunoglobulin Y antibodies in wild-type and alpha Gal knockout mice

Chicken antibodies (immunoglobulin Y; IgY) to the alpha Gal epitope (galactose alpha-1,3-galactose) bind to alpha Gal antigens of mouse and porcine tissues and endothelial cells in vitro and block human anti-alpha Gal antibody binding, complement activation and antibody-dependent cell-mediated lysis mechanisms. The activities and toxicity of anti-alpha Gal IgY have not been tested in vivo. In this study, we tested the effects of multiple injections of affinity-purified anti-alpha Gal IgY (AP-IgY) in both wild-type (WT) and alpha-1,3-galactosyltransferase knockout (Gal KO) mice. WT and Gal KO mice were injected once, twice, three, or four times intravenously (i.v.) with AP-IgY and killed at 1 hr or 24 hr. Mice displayed no toxicity to four injections of AP-IgY. Heart, lung, liver, kidney, spleen and pancreatic tissue were evaluated using immunohistochemical techniques for the presence of the alpha Gal epitope using the GSI-B4 lectin, and for bound IgY, as well as mouse IgM and IgG. The binding of AP-IgY antibodies to the endothelium of WT mouse tissues was essentially identical to the pattern of binding of the GSI-B4 lectin after injection of WT mice and death at 1 hr. WT mice killed 24 hr after i.v. injection of AP-IgY showed little remaining bound IgY in their endothelia, indicating that IgY is cleared over that time period. We also evaluated the blood drawn at the time of death for the presence of anti-alpha Gal IgY, anti-IgY IgM and anti-IgY IgG by enzyme-linked immunosorbent assay. Anti-alpha Gal IgY was almost undetectable in WT mouse sera at all injection and killing times. In contrast, Gal KO mouse sera showed increasing anti-alpha Gal IgY levels until 24 hr after the fourth injection, when anti-alpha Gal IgY levels were almost undetectable. Anti-IgY IgM and IgG levels in WT and Gal KO mouse sera showed a typical increase in anti-IgY IgM 24 hr after the second injection (3 days after the first injection) and an increase in anti-IgY IgG 24 hr after the third injection (5 days after the first injection). These results show that IgY binds to alpha Gal epitopes in the WT mice and is cleared sometime over a 24-hr time period and that IgY is an expected immunogen in mice eliciting a rather typical anti-IgY IgM and IgG response.