Differential Immune Response to Bioprosthetic Heart Valve Tissues in the α1,3Galactosyltransferase-Knockout Mouse Model

Structural valve deterioration (SVD) of bioprosthetic heart valves (BHVs) has great clinical and economic consequences. Notably, immunity against BHVs plays a major role in SVD, especially when implanted in young and middle-aged patients. However, the complex pathogenesis of SVD remains to be fully characterized, and analyses of commercial BHVs in standardized-preclinical settings are needed for further advancement. Here, we studied the immune response to commercial BHV tissue of bovine, porcine, and equine origin after subcutaneous implantation into adult α1,3-galactosyltransferase-knockout (Gal KO) mice. The levels of serum anti-galactose α1,3-galactose (Gal) and -non-Gal IgM and IgG antibodies were determined up to 2 months post-implantation. Based on histological analyses, all BHV tissues studied triggered distinct infiltrating cellular immune responses that related to tissue degeneration. Increased anti-Gal antibody levels were found in serum after ATS 3f and Freedom/Solo implantation but not for Crown or Hancock II grafts. Overall, there were no correlations between cellular-immunity scores and post-implantation antibodies, suggesting these are independent factors differentially affecting the outcome of distinct commercial BHVs. These findings provide further insights into the understanding of SVD immunopathogenesis and highlight the need to evaluate immune responses as a confounding factor.

Non-invasive oxygenation support in acutely hypoxemic COVID-19 patients admitted to the ICU: a multicenter observational retrospective study

Background

Non-invasive oxygenation strategies have a prominent role in the treatment of acute hypoxemic respiratory failure during the coronavirus disease 2019 (COVID-19). While the efficacy of these therapies has been studied in hospitalized patients with COVID-19, the clinical outcomes associated with oxygen masks, high-flow oxygen therapy by nasal cannula and non-invasive mechanical ventilation in critically ill intensive care unit (ICU) patients remain unclear.

Methods

In this retrospective study, we used the best of nine covariate balancing algorithms on all baseline covariates in critically ill COVID-19 patients supported with > 10 L of supplemental oxygen at one of the 26 participating ICUs in Catalonia, Spain, between March 14 and April 15, 2020.

Results

Of the 1093 non-invasively oxygenated patients at ICU admission treated with one of the three stand-alone non-invasive oxygenation strategies, 897 (82%) required endotracheal intubation and 310 (28%) died during the ICU stay. High-flow oxygen therapy by nasal cannula (n = 439) and non-invasive mechanical ventilation (n = 101) were associated with a lower rate of endotracheal intubation (70% and 88%, respectively) than oxygen masks (n = 553 and 91% intubated), p < 0.001. Compared to oxygen masks, high-flow oxygen therapy by nasal cannula was associated with lower ICU mortality (hazard ratio 0.75 [95% CI 0.58–0.98), and the hazard ratio for ICU mortality was 1.21 [95% CI 0.80–1.83] for non-invasive mechanical ventilation.

Conclusion

In critically ill COVID-19 ICU patients and, in the absence of conclusive data, high-flow oxygen therapy by nasal cannula may be the approach of choice as the primary non-invasive oxygenation support strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03905-5.

A randomized placebo-controlled phase II study of a Pseudomonas vaccine in ventilated ICU patients

Background

Currently, no vaccine against Pseudomonas is available. IC43 is a new, recombinant, protein (OprF/I)-based vaccine against the opportunistic pathogen, Pseudomonas aeruginosa, a major cause of serious hospital-acquired infections. IC43 has proven immunogenicity and tolerability in healthy volunteers, patients with burns, and patients with chronic lung diseases. In order to assess the immunogenicity and safety of IC43 in patients who are most at risk of acquiring Pseudomonas infections, it was evaluated in mechanically ventilated ICU patients.

Methods

We conducted a randomized, placebo-controlled, partially blinded study in mechanically ventilated ICU patients. The immunogenicity of IC43 at day 14 was determined as the primary endpoint, and safety, efficacy against P. aeruginosa infections, and all-cause mortality were evaluated as secondary endpoints. Vaccinations (100 μg or 200 μg IC43 with adjuvant, or 100 μg IC43 without adjuvant, or placebo) were given twice in a 7-day interval and patients were followed up for 90 days.

Results

Higher OprF/I IgG antibody titers were seen at day 14 for all IC43 groups versus placebo (P < 0.0001). Seroconversion (≥4-fold increase in OprF/I IgG titer from days 0 to 14) was highest with 100 μg IC43 without adjuvant (80.6%). There were no significant differences in P. aeruginosa infection rates, with a low rate of invasive infections (pneumonia or bacteremia) in the IC43 groups (11.2-14.0%). Serious adverse events (SAEs) considered possibly related to therapy were reported by 2 patients (1.9%) in the group of 100 µg IC43 with adjuvant. Both SAEs resolved and no deaths were related to study treatment. Local tolerability symptoms were mild and rare (<5% of patients), a low rate of treatment-related treatment-emergent adverse events (3.1–10.6%) was observed in the IC43 groups.

Conclusion

This phase II study has shown that IC43 vaccination of ventilated ICU patients produced a significant immunogenic effect. P. aeruginosa infection rates did not differ significantly between groups. In the absence of any difference in immune response following administration of 100 μg IC43 without adjuvant compared with 200 μg IC43 with adjuvant, the 100 μg dose without adjuvant was considered for further testing of its possible benefit of improved outcomes. There were no safety or mortality concerns.

Trial registration

ClinicalTrials.gov, NCT00876252. Registered on 3 April 2009.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1601-9) contains supplementary material, which is available to authorized users.

Biodistribution and Immunogenicity of Allogeneic Mesenchymal Stem Cells in a Rat Model of Intraarticular Chondrocyte Xenotransplantation

Xenogeneic chondrocytes and allogeneic mesenchymal stem cells (MSC) are considered a potential source of cells for articular cartilage repair. We here assessed the immune response triggered by xenogeneic chondrocytes when injected intraarticularly, as well as the immunoregulatory effect of allogeneic bone marrow-derived MSC after systemic administration. To this end, a discordant xenotransplantation model was established by injecting three million porcine articular chondrocytes (PAC) into the femorotibial joint of Lewis rats and monitoring the immune response. First, the fate of MSC injected using various routes was monitored in an in vivo imaging system. The biodistribution revealed a dependency on the injection route with MSC injected intravenously (i.v.) succumbing early after 24 h and MSC injected intraperitoneally (i.p.) lasting locally for at least 5 days. Importantly, no migration of MSC to the joint was detected in rats previously injected with PAC. MSC were then administered either i.v. 1 week before PAC injection or i.p. 3 weeks after to assess their immunomodulatory function on humoral and adaptive immune parameters. Anti-PAC IgM and IgG responses were detected in all PAC-injected rats with a peak at week 2 postinjection and reactivity remaining above baseline levels by week 18. IgG2a and IgG2b were the predominant and long-lasting IgG subtypes. By contrast, no anti-MSC antibody response was detected in the cohort injected with MSC only, but infusion of MSC before PAC injection temporarily augmented the anti-PAC antibody response. Consistent with a cellular immune response to PAC in PAC-injected rats, cytokine/chemokine profiling in serum by antibody array revealed a distinct pattern relative to controls characterized by elevation of multiple markers at week 2, as well as increases in proliferation in draining lymph nodes. Notably, systemic administration of allogeneic MSC under the described conditions did not diminish the immune response. IL-2 measurements in cocultures of rat peripheral blood lymphocytes with PAC indicated that PAC injection induced some T-cell hyporesponsiveness that was not enhanced in the cohorts additionally receiving MSC. Thus, PAC injected intraarticularly in Lewis rats induced a cellular and humoral immune response that was not counteracted by the systemic administration of allogeneic MSC under the described conditions.

Genetic engineering strategies to prevent the effects of antibody and complement on xenogeneic chondrocytes

Advances in animal transgenesis may allow using xenogeneic chondrocytes in tissue-engineering applications for clinical cartilage repair. Porcine cartilage is rejected by humoral and cellular mechanisms that could be overcome by identifying key molecules triggering rejection and developing effective genetic-engineering strategies. Accordingly, high expression of α1,2-fucosyltransferase (HT) in xenogeneic cartilage protects from galactose α1,3-galactose (Gal)-mediated antibody responses. Now, we studied whether expression of a complement inhibitor provides further protection. First, porcine articular chondrocytes (PAC) were isolated from non-transgenic, single and double transgenic pigs expressing HT and moderate levels of human CD59 (hCD59) and their response to human serum was assessed. High recombinant expression of human complement regulatory molecules hCD59 and hDAF was also attained by retroviral transduction of PAC for further analyses. Complement activation on PAC after exposure to 20 % human serum for 24 hours mainly triggered the release of pro-inflammatory cytokines IL-6 and IL-8. Transgenic expression of HT and hCD59 did not suffice to fully counteract this effect. Nevertheless, the combination of blocking anti-Gal antibodies (or C5a) and high hCD59 levels conferred very high protection. On the contrary, high hDAF expression attained the most dramatic reduction in IL-6/IL-8 secretion by a single strategy, but the additional inhibition of anti-Gal antibodies or C5a did not provide further improvement. Notably, we demonstrate that both hCD59 and hDAF inhibit anaphylatoxin release in this setting. In conclusion, our study identifies genetic-engineering approaches to prevent humoral rejection of xenogeneic chondrocytes for use in cartilage repair.

Inhibition of complement component C5 protects porcine chondrocytes from xenogeneic rejection

OBJECTIVE

Tissue-based xenografts such as cartilage are rejected within weeks by humoral and cellular mechanisms that preclude its clinical application in regenerative medicine. The problem could be overcome by identifying key molecules triggering rejection and the development of genetic-engineering strategies to counteract them. Accordingly, high expression of α1,2-fucosyltransferase (HT) in xenogeneic cartilage reduces the galactose α1,3-galactose (Gal) antigen and delays rejection. Yet, the role of complement activation in this setting is unknown.

DESIGN

To determine its contribution, we assessed the effect of inhibiting C5 complement component in α1,3-galactosyltransferase-knockout (Gal KO) mice transplanted with porcine cartilage and studied the effect of human complement on porcine articular chondrocytes (PAC).

RESULTS

Treatment with an anti-mouse C5 blocking antibody for 5 weeks enhanced graft survival by reducing cellular rejection. Moreover, PAC were highly resistant to complement-mediated lysis and primarily responded to human complement by releasing IL-6 and IL-8. This occurred even in the absence of anti-Gal antibody and was mediated by both C5a and C5b-9. Indeed, C5a directly triggered IL-6 and IL-8 secretion and up-regulated expression of swine leukocyte antigen I (SLA-I) and adhesion molecules on chondrocytes, all processes that enhance cellular rejection. Finally, the use of anti-human C5/C5a antibodies and/or recombinant expression of human complement regulatory molecule CD59 (hCD59) conferred protection in correspondence with their specific functions.

CONCLUSIONS

Our study demonstrates that complement activation contributes to rejection of xenogeneic cartilage and provides valuable information for selecting approaches for complement inhibition.

Bacteremia is an independent risk factor for mortality in nosocomial pneumonia: a prospective and observational multicenter study

Introduction

Since positive blood cultures are uncommon in patients with nosocomial pneumonia (NP), the responsible pathogens are usually isolated from respiratory samples. Studies on bacteremia associated with hospital-acquired pneumonia (HAP) have reported fatality rates of up to 50%. The purpose of the study is to compare risk factors, pathogens and outcomes between bacteremic nosocomial pneumonia (B-NP) and nonbacteremic nosocomial pneumonia (NB-NP) episodes.

Methods

This is a prospective, observational and multicenter study (27 intensive care units in nine European countries). Consecutive patients requiring invasive mechanical ventilation for an admission diagnosis of pneumonia or on mechanical ventilation for > 48 hours irrespective of admission diagnosis were recruited.

Results

A total of 2,436 patients were evaluated; 689 intubated patients presented with NP, 224 of them developed HAP and 465 developed ventilation-acquired pneumonia. Blood samples were extracted in 479 (69.5%) patients, 70 (14.6%) being positive. B-NP patients had higher Simplified Acute Physiology Score (SAPS) II score (51.5 ± 19.8 vs. 46.6 ± 17.5, P = 0.03) and were more frequently medical patients (77.1% vs. 60.4%, P = 0.01). Mortality in the intensive care unit was higher in B-NP patients compared with NB-NP patients (57.1% vs. 33%, P < 0.001). B-NP patients had a more prolonged mean intensive care unit length of stay after pneumonia onset than NB-NP patients (28.5 ± 30.6 vs. 20.5 ± 17.1 days, P = 0.03). Logistic regression analysis confirmed that medical patients (odds ratio (OR) = 5.72, 95% confidence interval (CI) = 1.93 to 16.99, P = 0.002), methicillin-resistant Staphylococcus aureus (MRSA) etiology (OR = 3.42, 95% CI = 1.57 to 5.81, P = 0.01), Acinetobacter baumannii etiology (OR = 4.78, 95% CI = 2.46 to 9.29, P < 0.001) and days of mechanical ventilation (OR = 1.02, 95% CI = 1.01 to 1.03, P < 0.001) were independently associated with B-NP episodes. Bacteremia (OR = 2.01, 95% CI = 1.22 to 3.55, P = 0.008), diagnostic category (medical patients (OR = 3.71, 95% CI = 2.01 to 6.95, P = 0.02) and surgical patients (OR = 2.32, 95% CI = 1.10 to 4.97, P = 0.03)) and higher SAPS II score (OR = 1.02, 95% CI = 1.01 to 1.03, P = 0.008) were independent risk factors for mortality.

Conclusions

B-NP episodes are more frequent in patients with medical admission, MRSA and A. baumannii etiology and prolonged mechanical ventilation, and are independently associated with higher mortality rates.

TNF, Pig CD86, and VCAM-1 Identified as Potential Targets for Intervention in Xenotransplantation of Pig Chondrocytes

Xenotransplantation of genetically engineered porcine chondrocytes may benefit many patients who suffer cartilage defects. In this work, we sought to elucidate the molecular bases of the cellular response to xenogeneic cartilage. To this end, we isolated pig costal chondrocytes (PCC) and conducted a series of functional studies. First, we determined by flow cytometry the cell surface expression of multiple immunoregulatory proteins in resting conditions or after treatment with human TNF-α, IL-1α, or IL-1β, which did not induce apoptosis. TNF-α and to a lesser extent IL-1α led to a marked upregulation of SLA I, VCAM-1, and ICAM-1 on PCC. SLA II and E-selectin remained undetectable in all the conditions assayed. Notably, CD86 was constitutively expressed at moderate levels, whereas CD80 and CD40 were barely detected. To assess their function, we next studied the interaction of PCC with human monoblastic U937 and Jurkat T cells. U937 cells adhered to resting and in a greater proportion to cytokine-stimulated PCC. Consistent with its expression pattern, pig VCAM-1 was key, mediating the increased adhesion after cytokine stimulation. We also conducted coculture experiments with U937 and PCC and measured the release of pig and human cytokines. Stimulated PCC secreted IL-6 and IL-8, whereas U937 secreted IL-8 in response to PCC. Finally, coculture of PCC with Jurkat in the presence of PHA led to a marked Jurkat activation as determined by the increase in IL-2 secretion. This process was dramatically reduced by blocking pig CD86. In summary, CD86 and VCAM-1 on pig chondrocytes may be important triggers of the xenogeneic cellular immune response. These molecules together with TNF could be considered potential targets for intervention in order to develop xenogeneic therapies for cartilage repair.

Serum levels of anti-alphaGalactosyl antibodies predict survival and peritoneal dialysis-related enteric peritonitis rates in patients undergoing renal replacement therapy

BACKGROUND

Anti-Galalpha1-3Gal antibodies (anti-alphaGal) represent a significant fraction of natural antibodies and were implicated in several disease states, yet their origin and physiological significance remain largely undisclosed.

METHODS

Under a prospective observational design, we estimated anti-alphaGal immunoglobulin G (IgG)/IgM and antipig hemolytic antibody (APA) levels in 133 patients starting dialysis therapy and again after a 1-year follow-up. We used baseline data to show correlations with demographic, nutritional, inflammatory, and anemia markers and analyzed their correlation with outcomes by using univariate and multivariate strategies of survival analysis.

RESULTS

Serum anti-alphaGal and APA levels showed wide baseline variability, but remained relatively stable in time. Both were measurable in dialysate of peritoneal dialysis (PD) patients, showing close correlation to serum levels. We observed no association between levels of anti-alphaGal/APA and nutritional markers, but showed direct correlations of anti-alphaGal IgM (P = 0.005) and APA levels (P = 0.001) with tumor necrosis factor alpha (TNF-alpha) levels. High APA levels also were associated with severe anemia (P = 0.006). High baseline anti-alphaGal IgM (P = 0.03) and APA levels (P = 0.045) predicted later risk for enteric peritonitis in PD patients. Finally, univariate and multivariate analyses showed a consistent association between high baseline anti-alphaGal IgM (P = 0.014) and APA (P = 0.021) levels and global risk for mortality during follow-up.

CONCLUSION

Anti-alphaGal IgM and APA levels at the start of dialysis therapy are significant predictors of later risk for mortality and, in PD patients, enteric peritonitis. Both correlate directly with TNF-alpha levels and, in the case of APA, severity of anemia in these patients.

Liver transplantation from maastricht category 2 non-heart-beating donors: a source to increase the donor pool?

INTRODUCTION

The demand for liver transplantation has increasingly exceeded the supply of cadaver donor organs. Non-heart-beating donors (NHBDs) may be an alternative to increase the cadaver donor pool. The outcome of 20 liver transplants from Maastricht category 2 NHBD was compared with that of 40 liver transplants from heart-beating donors (HBDs). After unsuccessful cardiopulmonary resuscitation (CPR), cardiopulmonary support with simultaneous application of chest and abdominal compression (CPS; n = 6) or cardiopulmonary bypass (CPB; n = 14) was used to maintain the donors.

RESULTS

At a minimum follow-up of 2 years, actuarial patient and graft survival rates with livers from Maastricht category 2 NHBD were 80% and 55%, respectively. Transplantation of organs from these donors was associated with a significantly higher incidence of primary nonfunction, biliary complications, and more severe initial liver dysfunction compared with organs from HBDs. The graft survival rates was 83% for livers from NHBDs preserved with CPS and 42% in those maintained with CPB.

Liver transplantation from maastricht category 2 non-heart-beating donors: a source to increase the donor pool?

INTRODUCTION

The demand for liver transplantation has increasingly exceeded the supply of cadaver donor organs. Non-heart-beating donors (NHBDs) may be an alternative to increase the cadaver donor pool. The outcome of 20 liver transplants from Maastricht category 2 NHBD was compared with that of 40 liver transplants from heart-beating donors (HBDs). After unsuccessful cardiopulmonary resuscitation (CPR), cardiopulmonary support with simultaneous application of chest and abdominal compression (CPS; n = 6) or cardiopulmonary bypass (CPB; n = 14) was used to maintain the donors.

RESULTS

At a minimum follow-up of 2 years, actuarial patient and graft survival rates with livers from Maastricht category 2 NHBD were 80% and 55%, respectively. Transplantation of organs from these donors was associated with a significantly higher incidence of primary nonfunction, biliary complications, and more severe initial liver dysfunction compared with organs from HBDs. The graft survival rates was 83% for livers from NHBDs preserved with CPS and 42% in those maintained with CPB.

Liver transplantation from Maastricht category 2 non-heart-beating donors

BACKGROUND

The demand for liver transplantation has increasingly exceeded the supply of cadaver donor organs. Non-heart-beating donors (NHBDs) may be an alternative to increase the cadaver donor pool.

METHODS

The outcome of 20 liver transplants from Maastricht category 2 NHBDs is compared with 40 liver transplants from heart-beating donors (HBDs). After unsuccessful cardiopulmonary resuscitation (CPR), cardiopulmonary support (CPS) with simultaneous application of chest and abdominal compression (n=6), and cardiopulmonary bypass (CPB; n=14), which was hypothermic (n=7) or normothermic (n=7), were used to preserve the organs from NHBDs. Factors that may influence the outcome of livers from Maastricht category 2 NHBDs were also investigated.

RESULTS

With a minimum follow-up of 2 years, actuarial patient and graft survivals with livers from Maastricht category 2 NHBDs were 80% and 55%, respectively. Transplantation of organs from these donors was associated with a significantly higher incidence of primary nonfunction, biliary complications, and more severe initial liver dysfunction compared with livers from HBDs. Graft survival was 83% in livers from NHBDs preserved with CPS and 42% in those maintained with CPB. No graft failed if the duration of warm ischemia did not exceed 130 min with CPR or CPS, and if the period of CPB did not surpass 150 min when this method was used after CPR, regardless if it was hypothermic or normothermic.

CONCLUSION

Livers from Maastricht type 2 NHBDs may be used for transplantation if the period of warm ischemia during CPR or CPS does not exceed 130 min. Hypothermic or normothermic CPB after CPR preserves liver viability for an additional 150 min.

Elicited non-anti-alphaGAL antibodies may cause acute humoral rejection of hDAF pig organs transplanted in baboons

The combination of immunosuppression and GAS 914, a polylysine containing alphaGal trisaccharide type 2 (TRI 2), has been associated with the prevention of acute humoral xenograft rejection (AHXR) in human decay accelerating factor (hDAF) pig-to-baboon xenotransplants. The aim of this study was to investigate the role of immunosuppression and GAS 914 to neutralize xenoantibodies before and after xenotransplantation. Eight baboons underwent heteropic heart xenotransplantation with hDAF transgenic pig organs, receiving GAS 914 before and after transplantation. Six baboons (Group A) were treated with an immunosuppression protocol that included cyclophosphamide (CyP), Neoral, ERL, and steroids. The other 2 baboons (Group B) were treated with the same immunosuppression but with a 50% reduction in the doses of CyP. No xenograft from Group A underwent acute humoral xenograft (median survival, 27 days), whereas the 2 in Group B experienced rejection (median survival, 6 days). GAS 914 depleted both immunoglobulin (Ig)M and IgG anti-alphaGAL disaccharide (DI), trisaccharide type 2 (TRI 2), and trisaccharide type 6 (TRI 6), before and after transplantation in Groups A and B. However, cytotoxic antibodies with other anti-pig specificities were elicited by the xenografts in Group B leading to AHXR.

Clinical transplantation: optimizing immunosuppressive treatment without compromise

Transplant 2001, the second joint meeting of the American Society of Transplantation and the American Society of Transplant Surgeons, was held from May 13 to 16, 2001, in Chicago, Illinois, U.S.A. The congress highlighted the constantly improving outcomes of organ transplantation. Incidence of rejection is under 15% for most transplants as a result of the availability of various immunosuppressants, which in turn permit an expanding number of treatment combinations as well as treatments increasingly tailored to the condition and needs of each patient.

Natural anti-alpha-galactosyl antibodies in patients undergoing peritoneal dialysis and hemodialysis

Anti-alpha-galactosyl antibodies (anti-Gal) seemingly mediate rejection of pig organs transplanted into humans and Old World monkeys. These natural antibodies appear to be produced by a subpopulation of B cells residing in the peritoneum. Therefore, peritoneal dialysis (PD) may have an impact on anti-Gal levels. In this cross-sectional study, blood anti-Gal levels were quantified by ELISA in 17 patients undergoing PD and 18 patients undergoing hemodialysis (HD), and the results were compared with those from a control group of 30 healthy blood donors. The effects of the mode of dialysis therapy and other epidemiologic variables on anti-Gal levels were also evaluated. The PD and HD patients were comparable with regards to age, sex, percentage having diabetes, time on dialysis, distribution of blood groups, and total serum levels of immunoglobulins A (IgA), G (IgG), and M (IgM). In patients and controls, IgG anti-Gal levels were not significantly different, but IgM anti-Gal levels were significantly lower in both PD and HD patients compared with controls. A nonsignificant trend toward lower IgM anti-Gal levels in PD patients compared with HD patients was also observed. IgG anti-Gal levels correlated positively with time on dialysis in the HD patients, but not in the PD patients. IgG anti-Gal levels also were found to be markedly elevated in three patients with chronic liver disease, but no other scrutinized variable appeared to influence IgG or IgM anti-Gal levels.

Goals for transplantation in the new millennium

Presentations at the XVIII International Congress of the Transplantation Society covered all key organ-specific and subspecialty areas of transplantation. Highlights were sessions under the auspices of two new sections of the Society, the International Xenotransplantation Association and the Section on Transplant Infectious Disease.

Basic and patient-oriented research in organ transplantation

The first joint congress of the American Society of Transplant Surgeons (ASTS) and the American Society of Transplantation (AST)--TRANSPLANT 2000--, was held May 13-17, 2000, in Chicago, Illinois, U.S.A. Results were presented on the latest clinical advances in organ transplantation, as well as aspects of basic research, where genetics studies and gene therapy approaches are gaining in importance. In the clinic, immunosuppressants continue to play a key role in transplantation, and the appearance of new drugs (e.g., mycophenolate mofetil, sirolimus) in recent years has led to increased possibilities of combination regimens, some including as many as four drugs. First clinical studies with three new immunosuppressants--FTY-720, leflunomide and rituximab) were also presented. The stellar presentation at TRANSPLANT 2000 was of a trial of pancreatic islet transplantation in type-1 diabetic patients which led to sustained insulin independence.

[Immunologic prognostic parameters in infection by the human immunodeficiency virus]

BACKGROUND

To evaluate the use of quantitative and functional immunologic parameters as prognostic markers of infection by the human immunodeficiency virus (HIV).

METHODS

The number of CD4 and CD8 lymphocytes, the CD4/CD8 ratio, the percentage of interleukin 2 (IL-2) receptors, the response to phytohemaglutinin (PHA) and the production of interferon tau (IFN-tau), were analyzed in 85 patients with HIV infection: 14 with acquired immunodeficiency syndrome (AIDS) (stage IV), 16 with persistent generalized adenopathies (stage III), and 55 asymptomatic patients (stage II). Similarly, a control group of 35 blood donors with negative HIV serology was studied.

RESULTS

Over a period of 30 months, 17 patients (5 of stage III and 12 of stage II) evolved to stage IV. In a multivariate analysis the decrease in the number of CD4 lymphocytes in stage II and the decrease in the production of IFN-tau in stage II and III were the parameters associated with progression to stage IV.

CONCLUSIONS

The decrease in the production of interferon tau in patients with infection by the human immunodeficiency virus in stage II and III as well as the decrease in the number of CD4 lymphocytes in stage II are prognostic factors associated with the evolution to stage IV of the infection.

[The use of immunologic parameters to assess the effectiveness of parenteral nutrition. Preliminary study]

Malnutrition leads to cellular and humoral immunological response disorders. A study protocol on malnourished patients has been designed in order to assess immune response mechanisms that may be altered due to malnutrition and may or may not recover once normal metabolic conditions have been restored prior to starting the patient on parenteral feeding and control. The immune response was assessed especially regarding immunoglobulin, lymphocyte subsets and mitogen response levels. It is important to know the different malnutrition-related immunologic disorders, disorders secondary to diseases that hinder correct oral feeding, and immunologic tests may be used to assess nutritional parameters. The malnourished patients included in this trial has to be free of any other immunologic or neoplastic disease, and not receive immune response suppression therapy. The trial patients showed lower total and relative CD3 and CD4 lymphocyte values at the onset of the study, although the former lymphocyte subset recuperated sooner at the expense of increasing CD8 lymphocytes, while CD4 lymphocytes still remained low after 15 days of parenteral nutrition. Immunoglobulin levels remained within normal limits. The mitogen response capacity, which was sensibly low at the beginning, recuperated in 50% of the cases treated with parenteral nutrition. This parameters may be used as an index to assess the nutritional status of these patients. The cases studies allowed us to conclude that there was a decrease in CD4 cells and mitogen response in malnourished patients. After 15 days of parenteral nutrition, the cells did not recuperate but their function measured in terms of phytohemagglutinin, was normal in 50% of the cases.

Disseminated intravascular coagulation and mesenteric venous thrombosis in fatal Amanita poisoning

1. A case of fatal Amanita phalloides poisoning in a 14-year-old boy is described. 2. The patient presented severe acute liver dysfunction, disseminated intravascular coagulation and refractory hypoxaemia, and died on the 9th day after mushroom ingestion. 3. Post-mortem examination revealed mesenteric venous thrombosis, massive liver necrosis and haemorrhagic pulmonary alveolitis.