Justin A. Roake

Dendritic cell chemotaxis and transendothelial migration are induced by distinct chemokines and are regulated on maturation.

The capacity of dendritic cells (DC) to initiate immune responses is dependent on their specialized migratory and tissue homing properties. Chemotaxis and transendothelial migration (TEM) of DC were studied in vitro. Immature DC were generated by culture of human monocytes in granulocyte‐macrophage colony‐stimulating factor and IL‐4. These cells exhibited potent chemotaxis and TEM responses to the CC chemokines macrophage inflammatory protein (MIP)‐1α, MIP‐1β, RANTES, and monocyte chemotactic protein‐3, and weak responses to the CC chemokine MIP‐3β and the CXC chemokine stromal cell‐derived factor (SDF)‐1α. Maturation of DC induced by culture in lipopolysaccharide, TNF‐α or IL‐1β reduced or abolished responses to the former CC chemokines but markedly enhanced responses to MIP‐3β and SDF‐1α. This correlated with changes in chemokine receptor expression: CCR5 expression was reduced while CXCR4 expression was enhanced. These findings suggest two stages for regulation of DC migration in which one set of chemokines may regulate recruitment into or within tissues, and another egress from the tissues.

Ischemia/Reperfusion Injury in Human Kidney Transplantation: An Immunohistochemical Analysis of Changes after Reperfusion

Organs used for transplantation undergo varying degrees of cold ischemia and reperfusion injury after transplantation. In renal transplantation, prolonged cold ischemia is strongly associated with delayed graft function, an event that contributes to inferior graft survival. At present, the pathophysiological changes associated with ischemia/reperfusion injury in clinical renal transplantation are poorly understood. We have performed an immunohistochemical analysis of pre- and postreperfusion biopsies obtained from cadaver (n = 55) and living/related donor (LRD) (n = 11) renal allografts using antibodies to adhesion molecules and leukocyte markers to investigate the intragraft changes after cold preservation and reperfusion. Neutrophil infiltration and P-selectin expression were detected after reperfusion in 29 of 55 (53%) and 24 of 55 (44%) cadaver renal allografts, respectively. In marked contrast, neutrophil infiltration was not observed in LRD allografts, and only 1 of 11 (9%) had an increased level of P-selectin after reperfusion. Immunofluorescent double-staining demonstrated that P-selectin expression resulted from platelet deposition and not from endothelial activation. No statistically significant association was observed between neutrophil infiltration and P-selectin expression in the glomeruli or intertubular capillaries despite the large number of cadaver renal allografts with postreperfusion changes. Neutrophil infiltration into the glomeruli was significantly associated with long cold ischemia times and delayed graft function. Elevated serum creatinine levels at 3 and 6 months after transplantation were also associated with the presence of neutrophils and platelets after reperfusion. Our results suggest that graft function may be influenced by early inflammatory events after reperfusion, which can be targeted for future therapeutic intervention.

Patterns of graft infiltration and cytokine gene expression during the first 10 days of kidney transplantation.

Understanding of the events preceding acute cellular rejection of kidney transplants would be useful in the development of immunosuppressive strategies to prevent rejection. Information about these events in humans has been scarce, because of the lack of early, serial, biopsy samples. We took daily fine needle aspirates from kidney allografts for the first 10 days after transplant. Samples were analyzed by morphological cytology of graft-infiltrating cells, and reverse transcriptase-polymerase chain reaction for detection of interleukin (IL)-2, IL-4, IL-6, IL-10, and gamma-interferon gene expression. During the first 4 days, all of the grafts developed a low-grade monocyte-rich mononuclear cell infiltrate, accompanied by IL-10 gene expression. Thereafter, the infiltrates either remained stable or intensified. Of the 13 grafts with dense infiltrates, seven developed graft dysfunction. The remaining six did not, despite significant interstitial infiltrates. Both rejecting and nonrejecting dense infiltrates were associated with a biphasic pattern of IL-2 and gamma-interferon gene expression, preceding and accompanying lymphocytic graft infiltration. Grafts that did not develop dense infiltrates had no detectable IL-2 or gamma-interferon gene expression and did not suffer cellular rejection during the study period. The development of both rejecting and nonrejecting infiltrates was strongly associated with DR mismatches between donor and recipient. IL-2 and gamma-interferon gene expression are necessary, but not sufficient, for the development of acute cellular rejection in the first 10 days of kidney transplantation, and are more closely associated with the period leading up to rejection than with the period of graft dysfunction.

PREEMPTIVE CADAVERIC RENAL TRANSPLANTATION-CLINICAL OUTCOME

Preemptive cadaveric renal transplantation (PCRT) maximizes the chance of maintaining high quality of life and may avoid the morbidity of dialysis and the associated financial costs. These benefits are offset by disadvantages, which include the possibility of transplantation many months before the need for dialysis, resulting in wasted organ function; an immediate risk of graft failure with conversion to a dialysis-dependent state; and uncertainty of the safety of PCRT. Patients who underwent PCRT between June 1976 and December 1994 at the Oxford Transplant Centre were compared with a matched cohort of first cadaveric transplant recipients who were dialysis-dependent when transplanted. The 116 patients in the PCRT cohort were well matched to the control group with respect to sex, age, blood group, HLA match, degree of sensitization, donor age, immunosuppression, and year of transplantation. Patient and graft survival were significantly better in the PCRT group. The difference in graft survival did not appear to be completely explained by better patient survival, as suggested by a trend toward better graft survival after excluding death with a functioning graft as a cause of failure. Among surviving grafts there were no significant differences in graft function as assessed by 1, 2, and 3 year plasma creatinine levels. In conclusion, PCRT appears to be safe and may even be associated with superior graft survival when compared with conventional transplantation. Early inclusion on a transplant waiting list with a view to PCRT can be justified with respect to the clinical outcome but the financial costs and implications for the utilization of cadaveric donor kidneys must also be considered.

Systemic lipopolysaccharide recruits dendritic cell progenitors to nonlymphoid tissues.

Dendritic cells (DC) are thought to be the “passenger leukocytes” that sensitize the recipients of organ transplants against graft antigens and trigger allograft rejection. DC originate from MHC class II-neg-ative (Ia-) progenitors in the bone marrow, which enter the tissues and develop into migratory cells with the specialized capacity to initiate primary immune responses. There is little information on which stimuli recruit DC progenitors to the tissues. Systemic administration of LPS to mice depletes Ia+ leukocytes from heart and kidney but recruits Ia- leukocytes (Roake JA, et al., see footnote 6). When these leukocytes were isolated and cultured overnight, Ia+ low density leukocytes developed that could stimulate primary T cell responses in vitro. Hearts from LPS-treated mice were transplanted to allogeneic recipients. One to 4 days after grafting, Ia+ donor cells were present in recipient spleens, localized to peripheral white pulp, and associated with CD4+, but not CD8+, T cells. Cells with the migratory characteristics of DC, therefore, originated from Ia- progenitors in the transplanted hearts. We conclude that LPS recruits Ia- DC precursors to the heart and kidneys. Hearts from LPS-treated donors were rejected by allogeneic recipients at the same tempo as normal hearts, implying that Ia- DC progenitors might ultimately contribute to heart graft rejection (direct sensitization). However, since hearts from cyclophosphamide-treated donors, which do not give rise to Ia+ cells in recipient spleens, were also rejected at a similar tempo, indirect sensitization could also play a role in heart graft rejection in this model.

Acute upper limb ischemia: a complication of coronary artery bypass grafting

We present the case of a patient with acute upper limb ischemia after radial artery harvest for coronary artery bypass grafting. This occurred despite adequate preoperative and intraoperative assessment with the Allen test, hand-held Doppler and radial artery backbleeding. A successful outcome was achieved by performing brachioradial bypass grafting using reversed cephalic vein.

Management of severe pancreatitis in renal transplant recipients

OBJECTIVEnThe authors determine if any aspects of the treatment of renal transplant patients with pancreatitis were of particular benefit with regard to graft and patient survival.nnnBACKGROUNDnThe incidence of pancreatitis in renal transplant patients is low (1%-2%), but the mortality of the disease approaches 100%. Although several descriptive reports have been published, there is no consensus-regarding management.nnnMETHODSnThe authors conduct a retrospective chart review.nnnRESULTSnTwenty-one patients were identified with posttransplant pancreatitis (1.3% incidence). The cause of pancreatitis was presumed to be maintenance immunosuppression in all cases. Patients were classified by dynamic computed tomography (CT) scans having 1) mild/edematous disease (4 patients), 2) localized abscess or pseudocyst (6 patients), or 3) severe disease (11 patients). Patients with mild/edematous pancreatitis did well with medical management. The six patients with localized abscess or pseudocyst were successfully treated with standard operative intervention. Of the 11 patients with severe disease, 6 had several days of intensive medical management before operation, and all died. The other five patients underwent early operative intervention based principally on CT scan findings, and all survived. The latter group had multiple operations and four of five had functioning renal allografts at discharge.nnnCONCLUSIONnThe severity of pancreatitis in the posttranplant patients may be difficult to assess by clinical criteria. Dynamic CT scanning is, therefore, essential in defining the extent of disease. Early, and perhaps repeated, operations may be lifesaving in those patients having CT scan findings of severe pancreatitis.

Cytomegalovirus infection and colonic perforation in renal transplant patients

Cytomegalovirus (CMV) infection in immunocompromised patients is a major cause of morbidity and mortality. A well-documented manifestation of gastrointestinal CMV infection is gastrointestinal haemorrhage. In contrast, CMV-associated intestinal perforation has rarely been reported after transplantation, although it is well documented in AIDS patients. Three patients are reported who received their first cadaveric renal transplant in 1994 and subsequently developed CMV disease. During the course of their CMV illness, which was treated with ganciclovir, each presented with clinical suspicion of peritonitis and proceeded to laparotomy. All three were found to have sigmoid colon perforations with histological evidence of CMV infection. Following bowel resection and defunctioning, two patients made an uneventful recovery and have had the continuity of their bowel restored, but one died of overwhelming sepsis within hours of surgery. The explanation for the apparent clustering of this rare condition in transplant patients is uncertain.

Effect of one-HLA-haplotype-matched and HLA-mismatched blood transfusions on recipient T lymphocyte allorepertoires

BACKGROUNDnPretransplant blood transfusion has a well-known beneficial effect on posttransplant graft survival. Recently, it has been proposed that the clinical benefit of transfusion is due to HLA-DR antigen sharing between the blood donor(s) and the recipient. Immunological studies have suggested that this might result from a functional deletion of donor-reactive cytotoxic T lymphocytes.nnnMETHODSnWe investigated frequencies of alloreactive lymphocyte precursors with cytotoxic or interleukin-2-producing helper function by limiting dilution analysis in 10 renal dialysis patients before and after transfusion with fresh, allogeneic whole blood. Five patients received blood transfusions from donors matched for one HLA haplotype (or one HLA-B-DR antigen) and the other five patients received blood from fully HLA-mismatched donors.nnnRESULTSnContrary to some previous reports, frequency analysis of cytotoxic T lymphocyte precursors revealed no significant differences between the two treatment groups in terms of development of blood donor-specific hyporesponsiveness after transfusion. Split-well analysis of cytotoxic T lymphocyte precursors reactive with single-mismatched HLA antigens demonstrated that the effects of transfusion on alloreactive specificity are complex and may vary depending on the particular antigens mismatched between the recipient and blood donor. Analysis of donor-specific helper T lymphocyte precursor frequencies revealed a significant decrease of interleukin-2-producing cells 3 months after transfusion in the total patient population. This effect was most prominent in the recipients of HLA-mismatched blood, but it also exhibited some degree of nonspecificity, as frequencies of third-party reactive helper T lymphocyte precursors were also significantly reduced.nnnCONCLUSIONSnOur overall results suggest that the degree of HLA matching between blood donor and recipient does not greatly influence the effect of blood transfusion on the T lymphocyte allorepertoire. The apparent induced down-regulation of helper T lymphocyte activity may play a role in the reported immunosuppressive effects of allogeneic blood transfusion.

Late reflush in clinical renal transplantation : Protection against delayed graft function not observed

Mechanical flushing of cadaveric kidneys with organ preservation fluid immediately before transplantation has been reported to be associated with improved early graft function. We report here the results of a prospective randomized controlled study of cadaveric renal transplantation after late reflush with organ preservation fluid in which no benefit with respect to delayed graft function was observed and, indeed, the protocol may have been harmful. The study was terminated after recruitment of only 18 patients (9 to each arm) because postreperfusion biopsies of reflushed kidneys contained unusual features, including abnormal cellular debris within the tubules or eosinophilic proteinaceous material within Bowmans capsule. These features were not present in the control kidneys. Acute tubular necrosis and biopsy-proven acute rejection episodes were more frequently seen in the reflushed kidneys, but at 1 year there was no significant difference in the function of the surviving grafts.