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.

Simultaneous pancreas-kidney transplantation in the mycophenolate mofetil/tacrolimus era: evolution from induction therapy with bladder drainage to noninduction therapy with enteric drainage

BACKGROUND

In the past, enteric drainage or the omission of induction immunotherapy has been shown to be predictive of suboptimal outcomes of simultaneous pancreas-kidney (SPK) transplantation. We have reassessed the need for bladder drainage and induction immunotherapy to optimize the outcome of SPK transplantation.

METHODS

One hundred consecutive recipients of SPK transplants who received mycophenolate mofetil and tacrolimus immunosuppression were studied. The first 50 recipients had bladder-drained pancreas allografts and received induction immunotherapy. The results were compared with the next 50 recipients who had enteric-drained pancreas allografts, which included a subgroup (n = 17 patients) who were randomized to receive no induction immunotherapy.

RESULTS

The 1-year actuarial patient, kidney, and pancreas survival rates in the bladder-drainage group were 98.0%, 94.0%, and 94.0%, respectively. The 1-year actuarial patient, kidney, and pancreas survival rates in the enteric-drainage group were 96.8%, 96.8%, and 89.4%, respectively. In the enteric-drainage group, the incidence of rejection at 1 year was 6.1% in recipients who received induction therapy versus 23.5% in recipients who did not receive induction therapy. The average number of readmissions per recipient was 1.8 in the bladder-drainage group versus 0.9 in the enteric-drainage group.

CONCLUSIONS

Primary enteric drainage of the pancreas allograft in recipients of SPK transplantation is the preferred surgical technique in the tacrolimus/mycophenolate mofetil era.

Synthetic peptides which inhibit the interaction between C1q and immunoglobulin and prolong xenograft survival

BACKGROUND

Acute vascular xenograft rejection (AVXR), also termed delayed xenograft rejection (DXR), occurs when hyperacute rejection (HAR) is prevented by strategies directed at xenoreactive natural antibodies and/or complement activation. We have hypothesized that AVXR/DXR is initiated in part by early components of the complement cascade, notably C1q. We have developed synthetic peptides (termed CBP2 and WY) that interfere with the interaction between C1q and antibody.

METHODS

CBP2 and the WY-conjugates were used as inhibitors of immunoglobulin aggregate binding to solid phase C1q. Inhibition of complement activation by the peptides of the classical system was determined using lysis assays with sensitized sheep red blood cells or porcine aortic endothelial cells as targets and of the alternate complement pathway using guinea pig red blood cells as targets. Two transplant models were used to study the effects of administering peptides to recipients: rat heart transplant to presensitized mouse, and guinea heart transplant to PVG C6-deficient rats.

RESULTS

CBP2 and WY-conjugates inhibited immunoglobulin aggregate binding to C1q. The peptides also inhibited human complement-mediated lysis of sensitized sheep red blood cells and porcine aortic endothelial cells in a dose-dependent manner and the WY-conjugates prevented activation of the alternate complement pathway as shown by inhibition of guinea pig red blood cells lysis with human serum. In addition, the use of the peptides and conjugates resulted in significant prolongation of xenograft survival.

CONCLUSIONS

The CBP2 and WY peptides exhibit the functional activity of inhibition of complement activation. These peptides also prolong xenograft survival and thus provide reagents for the study of the importance of C1q and other complement components in transplant rejection mechanisms.

Laparoscopic live donor nephrectomy--is it safe?

BACKGROUND

Laparoscopic live donor nephrectomy (LDN) is a less invasive alternative to open nephrectomy (ODN) for living kidney donation. Concerns have been raised regarding the safety of LDN, the short and long term function of kidneys removed by LDN, and a potential higher incidence of urologic complications in LDN transplant recipients.

METHODS

Between October 1997 and May 1999, 80 LDNs were performed at our center. All patients were followed longitudinally with office visits and telephone interviews. These LDNs were compared with 50 ODN performed from January 1996 to October 1997.

RESULTS

LDN procedures took significantly longer than ODN (4.6 vs. 3.1 hr). However, LDN was associated with significant reduction in i.v. narcotic use, a rapid return to diet, and shorter hospital stay. Of the 80 LDN procedures, a total of 75 (94%) were completed laparoscopically. Five patients were converted to laparotomy: three for hemorrhage and two for complex vascular anatomy. ODN conversion was associated with large donor body habitus and/or obesity. Seven LDN patients had minor complications and 4 had major complications. All major complications consisted of vascular injuries (2 lumbar vein injuries, 1 renal artery, and 1 aortic injury). All patients made complete recoveries. All LDN kidneys functioned immediately posttransplant. We have observed 100% patient and 97% 1-year actuarial graft survival in LDN transplant recipients. There have been no short-or long-term urologic complications in this series.

CONCLUSION

With increasing experience and standardization of technique, LDN is a safe and effective procedure. Patients undergoing LDN demonstrate clinically significant, more rapid postoperative recoveries and shorter hospital stays than ODN patients. Excellent initial graft function and long-term graft survival have been observed with LDN kidneys. Urologic complications can be avoided. LDN has become the preferred surgical approach for living kidney donation at our center.

Mutations of the human tyrosinase gene associated with tyrosinase related oculocutaneous albinism (OCA1). Mutations in brief no. 204. Online

Mutations in the human tyrosinase gene produce tyrosinase-related oculocutaneous albinism (OCA1, MIM #203100). Tyrosinase is a copper containing enzyme and is responsible for catalyzing the rate limiting step in melanin biosynthesis, the hydroxylation of tyrosine to dopaquinone. We report 13 new mutations in the tyrosinase gene associated with OCA1A (without pigment) and OCA1B (with pigment) including 9 missense mutations (H19Q, R521, R77C, G97R, C289R, L312V, P313R, F340L and H404P), two nonsense mutations (W80X and R116X) and two frameshift mutations (53delG and 223 delG). Our previous work has defined clusters of missense mutations that appear to represent functional domains of the enzyme, and three of the missense mutations fall into these clusters including two (F340L and H404P) that flank the copper B bindng site and the missense mutation R52I that is located in the amino terminal end cluster of the protein. The G97R missense mutation is the first identified within the epidermal growth factor (EGF)-like sequence and the H19Q missense mutation alters the cleavage site of the signal peptide sequence. Mutational analysis can provide a definitive diagnosis of the type of OCA as well as help structure/function analysis.

Molecular analysis of an extended Palestinian family from Israel with monilethrix

We describe the molecular analysis of a large three generation Palestinian family segregating for monilethrix. Previous reports have shown that mutations in type-II hair cortex keratin genes, hHb1 and hHb6, are associated with monilethrix. Genetic linkage analysis performed on this family using markers flanking the hHb6 gene exhibited strong evidence for linkage. Sequence analysis revealed a nucleotide substitution of G --> T at nucleotide 1230 resulting in a glutamic acid to aspartic acid amino acid substitution at codon 410, identical to that reported in a French family. The family in our study provides further evidence that mutations of the hHb6 gene are responsible for monilethrix.

Mycophenolate mofetil and tacrolimus as primary maintenance immunosuppression in simultaneous pancreas-kidney transplantation: initial experience in 50 consecutive cases

BACKGROUND

The current study examines the use of mycophenolate mofetil (MMF) and tacrolimus as primary immunosuppression in simultaneous pancreas-kidney (SPK) transplantation. In addition, analyses of the rates of conversion from one immunosuppressive agent to another, and its subsequent consequences with respect to outcomes were determined. Quality of graft function, infections, and effect on preexisting essential hypertension are also described.

METHODS

Immunosuppression consisted of quadruple therapy with antithymocyte globulin induction, tacrolimus, MMF, and prednisone. Patient and graft survival and rejection rates in 50 consecutive SPK recipients, followed for a minimum of 3 months and a mean of 14 months (range: 3-34 months), are described.

RESULTS

Thirty-nine of 50 (78%) patients tolerated the MMF/tacrolimus combination long-term (mean duration of follow-up: 14+/-7 months). Nine of 50 patients (18%) were converted to Neoral, and 4 patients were converted to azathioprine as a substitute for MMF. The 2-year actuarial patient, kidney, and pancreas survival rates were 97.7%, 93.3%, and 90.0%, respectively. At 6 months after transplant, the overall incidence of acute rejection was 16%. There was a statistically significant (P< or =0.04, Cox-Mantel test) difference in the rate of rejection associated with conversion to Neoral. The incidence of rejection 6 months after transplant in the group maintained on MMF/tacrolimus was 10.2% vs. 44.4% in the group converted to Neoral (P< or =0.04, Cox-Mantel test). Overall, the 1-year actuarial cumulative incidence of tissue-invasive cytomegalovirus disease was 6.6%. There were no cases of fungal infections or post-transplant lymphoproliferative disorders. One patient developed Kaposi's sarcoma 10 months after transplant. With respect to hypertensive disease, 60% (12/20) of the patients who required pharmacologic control of blood pressure before transplant were off all antihypertensive medications at 1 year after transplant. An additional 20% (4/20) of patients had a reduction in the number of medications required to control blood pressure at 1 year after transplant.

CONCLUSIONS

We conclude that the combination of MMF and tacrolimus as primary immunosuppression for SPK transplantation results in excellent patient and graft survival rates, a very low rate of acute rejection, and low rates of infection and malignancy.

Identification of a novel transcript produced by the gene responsible for the Hermansky-Pudlak syndrome in Puerto Rico

Hermansky-Pudlak Syndrome (HPS) is a rare, autosomal recessive disorder that is characterized by oculocutaneous albinism, a predisposition to mild bleeding caused by storage-pool deficient platelets, and a ceroid storage disorder. A gene responsible for HPS in Puerto Rico maps to chromosome 10q2 and isolation of the gene has been reported. We have now identified a variant HPS cDNA that contains the same 5' sequence as the published HPS gene and a unique 3' sequence. Analysis of genomic DNA suggests that the two cDNA are derived from alternative transcripts of a single gene; two polyadenylated transcripts were found in normal human melanocytes, human bone marrow cells, human melanoma cells, lymphoblastoid cell lines, and megakaryocytic leukemia cells by reverse transcriptase polymerase chain reaction and northern analysis. The splicing exhibited by this gene is identical to the splicing found to produce two alternative transcripts of the Chediak-Higashi Syndrome gene, another pigment disorder exhibiting platelet storage pool deficiency. These studies show that the HPS gene on chromosome 10 is complex and may have more than one biologically active transcript.

Cellular localization of latent murine cytomegalovirus

Herpesviruses typically establish latent infection in their hosts. The cell(s) responsible for harboring latent virus, in most cases, is not known. Using immunofluorescence and PCR-in situ hybridization (PISH), a technique which combines the sensitivity of PCR with the localization and specificity of in situ hybridization, we provide the first direct evidence that endothelial cells are a major site of murine cytomegalovirus (MCMV) DNA in latently infected animals. These findings are consistent with existing knowledge of the biological behavior of CMV, in particular the transmission of latent CMV by solid organ and bone marrow transplantation, in both human and animal models. In addition, we have localized MCMV DNA in the lung alveolar macrophage and in bone marrow cells. Our findings confirm that bone marrow-derived hematopoietic cells are a site of CMV latency and further suggest that bone marrow may be a reservoir of infected progeny capable of migrating into the circulation and establishing latency in various tissues. These findings provide clearly needed insight into the site of latent infection which is central to an understanding of the mechanisms of reactivation.

The role of PCR in the diagnosis and management of CMV in solid organ recipients: what is the predictive value for the development of disease and should PCR be used to guide antiviral therapy?

Cytomegalovirus remains a significant source of morbidity and mortality in immunocompromised hosts. The increased sensitivity of molecular diagnostic techniques (PCR, antigenemia) has resulted in our ability to detect viral replication earlier in the posttransplant period, before the onset of symptoms. With the advent of effective antiviral therapy, "preemptive therapy," guided by sensitive, early and specific predictors of CMV disease, has become a realistic objective. Although multiple studies have analyzed the sensitivity and specificity of these tests, their predictive value for the development of disease has not been defined. The purpose of this study was to evaluate the predictive value of a positive CMV PCR in the setting of solid abdominal organ transplantation. A total of 476 PCR assays were performed on 134 transplant recipients (102 kidney, 19 kidney/pancreas, 11 liver, 2 other) either as protocol serial samples or as dictated by clinical events. All samples were concomitantly analyzed using standard virological assays for CMV including culture, shell vial, and serology. Patients with any CMV seropositive donor/recipient (D/R) combination received ganciclovir prophylaxis in conjunction with antilymphocyte induction for 14 days. No subsequent CMV prophylaxis was used. The positive predictive value was 55% in all seropositive donor/recipient combinations. The highest risk group (seronegative recipient of seropositive donor) showed the highest positive predictive value, whereas seropositive recipients of either seropositive or seronegative donors showed positive predictive values of 45% and 25%, respectively. Negative predictive value was 100% for all groups. Early detection of CMV infection has important implications for patient management, including preemptive therapy, which can be guided by PCR, especially in high risk (D+/R-) patients.

Early histopathology of small intestinal discordant xenografts

A descriptive study of a new model enabling serial biopsies of ongoing hyperacute rejection of small intestinal discordant xenografts is presented. In a series of guinea-pig-to-Lewis rat small bowel xenotransplants (n=7), aboral free ends of Thierry-Vella loops constructed from the graft were sequentially biopsied at one-minute intervals up to ten minutes post-reperfusion and less frequently thereafter. In a guinea pig-to-guinea pig (n=6) isograft series, biopsy controls for preservation/ischemia-reperfusion injury were obtained. Xenoantibody sequestration in this model was evaluated in a separate series of transplants, utilizing an ELISA assay for rat anti-guinea pig natural antibodies. Pathologic evaluation revealed a unique series of events characterized with microcirculatory failure and thrombosis progressing from the submucosal vasculature to the lumen. Within the system's detection limits, complement deposition and P-selectin expression occurred as early as one minute post-reperfusion, preceding the staining for IgM and IgG. Using rat serum ELISAs, no significant difference in xenoantibody sequestration was detected between the xenograft and isograft groups. The guinea pig-to-rat discordant small bowel xenotransplantation is an efficient small animal model to dissect the very early pathophysiologic events during hyperacute rejection.

Frequency of hyperkalemia in recipients of simultaneous pancreas and kidney transplants with bladder drainage

Hyperkalemia is the most frequent electrolyte abnormality found in whole organ transplant recipients receiving either cyclosporine (CsA) or tacrolimus (FK506). Recipients of a simultaneous pancreas kidney (SPK) transplant with bladder drainage may be particularly susceptible to hyperkalemia secondary to sodium loss from the bladder-drained pancreas, leading to decreased sodium delivery to potassium secretory sites of the kidney. We looked at the incidence of hyperkalemia in 34 type I diabetic SPK recipients transplanted at our center over the period from 1993 to 1995 and compared this with a cohort of 25 type I diabetic recipients of a kidney alone (K(Tx)) transplant. The incidence of hyperkalemia was 73.5% in recipients of an SPK, while it was 44% in K(Tx) recipients (P<0.05). CsA levels were higher, on average, in the SPK group (339 ng/ml+/-62 versus 272 ng/ml+/-58 in the K(Tx) group, P<0.05). However, CsA levels were not different between groups at the time of hyperkalemia, 320+/-74 versus 298+/-49 for SPK and K(Tx), respectively. CsA levels at the time of hyperkalemia were not different from those at the time of normokalemia. Other medications, serum bicarbonate, and renal function were not different in the groups. SPK recipients appear to have a greater incidence of hyperkalemia than kidney alone transplant recipients. This difference cannot be explained by higher acute CsA levels, other medications, or worse renal function. The increased incidence of hyperkalemia may, in part, be secondary to decreased sodium delivery to the transplanted kidney.

Acyclovir triphosphate inhibits the diagnostic polymerase chain reaction for cytomegalovirus

Immunocompromised patients are frequently treated with guanine analogs such as acyclovir and ganciclovir. Acyclovir triphosphate, the active intracellular metabolite of acyclovir, exerts its antiviral effect by inhibiting herpesviral DNA polymerases through premature chain termination. PCR has recently been used for early detection of cytomegalovirus. However, we and others have experienced false-negative results for cytomegalovirus-PCR in patients on both acyclovir and ganciclovir. The impact of these agents on PCR assay is unknown. In an attempt to investigate the role of guanosine analogs in these false-negative results, we exposed the DNA-PCR for murine beta-actin, a murine CMV IE gene sequence, and a human CMV IEA1 product, to phosphorylated acyclovir derivatives. Varying concentrations of acyclovir-5'-triphosphate (final: 70-6000 microM) in the reaction mix resulted in an absence of detectable product at or above 490-670 microM. Inhibition was not observed with up to 1400 microM acyclovir-monophosphate. Increasing the Taq concentration to 10 units/100 microL stopped the inhibition. Our data demonstrate that acyclovir-5'-triphosphate inhibits PCR amplification of various gene products in a concentration-dependent manner. Furthermore, this inhibition appears to be specifically directed against the Taq polymerase and can be completely reversed by higher concentrations of the enzyme. Thus, false-negative PCR results for a viral gene product in patients under prophylaxis/treatment with acyclovir could potentially be due to contamination by acyclovir triphosphate. Therefore, negative PCR results in these patients need be interpreted with caution.

Combined transplantation of small and large bowel. FK506 versus cyclosporine A in a porcine model

Clinically, FK506 is superior to CsA after solitary small bowel transplantation (SBTx). Development of diarrhea after SBTx has been the rationale for adding the colon to small bowel grafts. However, the additional lymphoid and bacterial content transferred with total small plus large bowel transplants (TBTx) might aggravate the alloimmune response-rejection and graft-versus-host disease (GVHD)-and increase the risk of infection. We studied the incidence of rejection, GVHD, and infection after TBTx and the impact of CsA versus FK506. We performed orthotopic TBTx with portal drainage after total enterectomy in outbred Yorkshire Landrace pigs, divided into 3 groups: control pigs (n=6) received no immunosuppression; CsA pigs (n= 14) received CsA (5 mg/kg), antilymphocyte globulin (10 mg/kg for 10 days), prednisone (2 mg/kg), and AZA (2.5 mgtkg); and FK506 pigs (n=9) received FK506 (0.2 mg/kg) and prednisone (2 mg/kg). Trough CsA whole blood levels were >400 ng/ml for the first 7 days and >200 ng/ml thereafter. FK506 levels were > 15 ng/ml. We excluded from further analysis 5 early deaths (<3 days) due to anesthesiologic (n=2) or technical reasons (n=3). Median survival of control pigs was 9.5 days (range, 4-13). Cyclosporine did not extend survival: median, 9 days (range, 5-31) (P=0.6). FK506 prolonged survival: median, 37 days (range, 21-49) (P<0.001 vs. control and CsA pigs). Of FK506 pigs, 60% gained weight (+75 g/day), whereas 100% of controls and 75% of CsA pigs lost weight (-550 g/day and -300 g/day, respectively). All control pigs died of rejection within 2 weeks versus none of the FK506 pigs. However, 36% of CsA pigs died of rejection. Groupwise comparison showed less rejection in FK506 versus control pigs (P<0.001) and in FK506 versus CsA pigs (P<0.03), but no difference between CsA and control pigs. None of the control pigs died of GVHD versus 18% of CsA pigs (by day 31) and 37% of FK506 pigs (by day 49). Groupwise comparison showed increased GVHD in FK506 versus control pigs (P<0.001) and a tendency toward increased GVHD in FK506 versus CsA pigs (P=0.08). None of the control pigs died of infection alone versus 22% of CsA pigs (by day 31) and 67% of FK506 pigs (by day 49). Groupwise comparison showed increased infection in FK506 versus control pigs (P<0.001). We detected significant endotoxemia early and late postoperatively. But we saw no specific correlation between endotoxemia, rejection, GVHD, or infection. Based on this study, we have drawn several conclusions: (1) In untreated pigs, TBTx provokes a severe rejection response, but no lethal GVHD. (2) Cyclosporine and particularly FK506 pigs have a high incidence of infection and lethal GVHD, a complication that we had not seen after solitary SBTx. (3) FK506 is superior to CsA in controlling rejection and in prolonging graft and recipient survival; FK506, however, does not reduce GVHD, but rather tends to augment it. (4) TBTx causes endotoxemia. As with solitary SBTx, FK506 is superior to CsA after TBTx. However, longterm survival is difficult to achieve on FK506 recipients because of the development of GVHD and infection.

A comparison of cyclosporine A and cyclosporine G in a rabbit heterotopic cardiac transplant model: graft outcome and histological findings

Cervical heterotopic heart transplants were performed on 20 male New Zealand white rabbits comprising 4 treatment groups. Animals in each group were injected daily via the marginal ear vein and received one of the following regimes: Cyclosporine A, 10 mg/kg/day; Cyclosporine G, 15 mg/kg/day; cremophor-El, 3ml/day; or normal saline. Measurement of 24 hour trough blood concentrations revealed no significant differences between the average concentrations of Cyclosporine A and Cyclosporine G. Animals were examined daily and the cervical allografts assessed by palpation for viability/rejection. The duration of the study ended for each animal when the graft stopped beating at which time the animals were euthanized and the transplanted heart and native kidneys harvested and processed for light microscopy evaluation of rejection and drug toxicity, respectively. Graft survival in the Cyclosporine A group significantly surpassed that seen in the Cyclosporine G group as well as the control groups, whereas in animals treated with Cyclosporine G, graft survival was not different from controls. In the native kidney, there were no differences in glomerular tuft area or volume density amongst drug-treated or control animals. In contrast, tubule atrophy and interstitial fibrosis were markedly greater in Cyclosporine A-treated vs Cyclosporine G-treated animals. The results of this study indicate that, whereas Cyclosporine G is less nephrotoxic than Cyclosporine A, given equivalent blood concentrations Cyclosporine A delays rejection of a cardiac allograft significantly longer than Cyclosporine G in this animal species.