[Immunosuppressive treatment: surveillance, toxicity, prospects]

Imurel and glucocorticosteroid were long the only effective immunosuppressive agents used in prevention of renal allograft rejection. In the 80s, the discovery of a macrolide, cyclosporine A, led to considerable improvement in survival of transplants (around 10 to 20%). Imurel, corticosteroid and cyclosporine constitute the reference immunosuppressive treatment. The mode of use is not fixed and depends on the usage in each transplantation centre. The numerous side effects of these agents sometimes limit their use and, for some, can lead to stopping treatment. Close regular follow-up is required to ensure optimum efficacy and minimum toxicity. Present research in post-transplantation treatment is testing new molecules with powerful immunosuppressive activity, i.e., FK506, rapamycine, mycophenolic acid, sodium brequinar and 15 deoxyspergualine. Some act like Imurel (brequinar, mycophenolic acid), while FK506 and rapamycine have a mechanism of actions that are related to those of cyclosporine A. 15 deoxyspergualine has a different mechanism. The use of these agents in the near future, in association, will allow reducing the nontoxic levels of dosages of each, while maintaining an effective immunosuppression threshold.

Effect of plasma protein adsorption on protein excretion in kidney-transplant recipients with recurrent nephrotic syndrome

BACKGROUND

Among patients with the idiopathic nephrotic syndrome who have focal and segmental glomerulosclerosis and undergo renal transplantation, 15 to 55 percent have recurrent nephrotic syndrome. The recurrence may be caused by a plasma factor or factors that increase glomerular permeability, because plasma exchange transiently decreases or abolishes proteinuria in some patients. We studied the effect on proteinuria of the removal of protein (mostly immunoglobulins) by adsorption onto protein A from the plasma of patients with recurrent nephrotic syndrome.

METHODS

Eight patients were treated with one to three cycles of two to seven 1-day sessions of protein adsorption, and the patients' urinary protein excretion was measured repeatedly. Their immunosuppressive regimens were not changed during the treatment. The adsorbed proteins were eluted from the protein A and injected into rats, and the urinary albumin excretion of the rats was measured.

RESULTS

The protein-adsorption treatment consistently decreased urinary protein excretion by an average of 82 percent at the end of a cycle (P < 0.001). In one patient proteinuria disappeared, and in another urinary protein excretion remained below 2.5 g per day with repeated cycles of protein adsorption. In all but one patient the effect of adsorption was limited in time, with a return to the preadsorption level of protein excretion within a maximum of two months. The administration to rats of material eluted from the protein A increased urinary albumin excretion 2.9- to 4.6-fold (P < 0.001 and P = 0.005, respectively). Although protein A primarily binds immunoglobulins, the active fraction of the eluted proteins had a molecular weight below 100,000, indicating that immunoglobulin was not directly involved.

CONCLUSIONS

Adsorption of plasma protein decreases urinary protein excretion in patients with recurrence of the nephrotic syndrome after renal transplantation. Studies of the adsorbed proteins should provide information about the mechanism of this disease.

Prevention of acute rejection episodes with an anti-interleukin 2 receptor monoclonal antibody. II. Results after a second kidney transplantation

The focus of progress in transplantation immunosuppression is to achieve more specific immunosuppression with monoclonal antibodies. We have already shown that the efficacy of 33B3.1, a rat monoclonal Ig2A directed against the human IL-2 receptor, was similar to that of rabbit antithymocyte globulin in the prevention of acute rejection in first kidney transplants. A similar comparative analysis has been made in 40-sec renal transplants. ATG (1 mg/kg/day) or 33B3.1 (10 mg/day) was administered during the first 10 days postgrafting in association with corticosteroids and azathioprine. Cyclosporine was introduced on day 9 and azathioprine/CsA constituted the patient's maintenance treatment after day 45. Rejection treatment consisted of equine antilymphocyte globulin in both cases and of steroid boluses when patients were under Cyclosporine. One patient in each group died. Graft survival was 90%, 85%, and 79% in the ATG group (n = 20) and 100%, 89%, and 89% in the 33B3.1 group (n = 20) at 3, 12, and 24 months, respectively. Of the ATG group patients, 45% and 40% in the 33B3.1 group had at least one rejection episode, half the episodes in the MoAb cohort occurring under 33B3.1, vs. none in the ATG group. Transplant function was similar in both groups. Viral infections appeared to be more frequent with ATG (60%) than with 33B3.1 (12%), with CMV accounting for half of these in the ATG group, and none in the MoAb group. Tolerance of both agents was good. Of the 33B3.1 recipients, 70% developed anti-33B3.1 antibodies. From these data, we conclude that this anti-IL-2 receptor MoAb seems less effective than rabbit ATG as induction treatment in second kidney transplant patients.

Cadaveric renal transplantation after 60 years of age. A single center experience

We report the outcome of 121 cadaveric renal transplants performed in our institution between September 1985 and April 1992 in 117 patients, aged 60-71 years (mean 63 years) at the time of transplantation. Compared to 640 patients 20-59 years of age transplanted during the same study period, a nonstatistically significant difference was observed in the 5-year actuarial patient (80% and 90%, respectively, in recipients over and under 60 years of age) and transplant (80% and 72%, respectively, in recipients over and under 60 years of age) survival rates. However, elderly patients had significantly lower survival than recipients 20-29 years of age (P < 0.009). Fourteen patients died (all but one with a functioning graft) due to cardiovascular diseases (5%; 42.8% of total deaths), infections (3%; 28.6% of total deaths), and gastrointestinal complications (3%; 28.6% of total deaths). Younger patients showed a similar and nonsignificantly different incidence of cardiovascular- (35%) and infectious-(30%) related deaths. The incidence of acute rejection episodes and cytomegalovirus (CMV) infectious episodes was 27% and 24%, respectively, during the 1st post-transplant year. Ongoing acute rejection and CMV infectious episodes were significantly higher in patients who died than in those still alive (P < 0.002 and P < 0.02, respectively). Cyclosporin maintenance therapy was well tolerated in all patients but one, and 64% of the patients could be maintained without steroids. These data indicate that cadaveric renal transplantation is a safe and effective procedure in the management of chronic renal failure of selected patients 60 years of age or older.

Prevention of acute rejection episodes with an anti-interleukin 2 receptor monoclonal antibody. I. Results after combined pancreas and kidney transplantation

A prospective, randomized trial was conducted to evaluate the short-term and long-term effects of induction immunosuppression with the rat IgG 2a monoclonal antibody 33B3.1, directed against the human alpha chain of the interleukin 2-receptor, following primary, cadaveric, combined pancreas and kidney transplantation. Forty patients were randomly assigned to receive 10 mg/day of 33B3.1 (n = 20) or 1.5 mg/kg/day of rabbit antithymocyte globulin (n = 20) for the first 10 postoperative days. Azathioprine, low-dose corticosteroids, and cyclosporine were given in association with either 33B3.1 or ATG. All 40 patients received the entire 10-day bioreagent course and no episode of rejection was observed during this period. Although the incidence of rejection did not significantly differ within the first, second, and third postoperative months (ten 33B3.1 and 6 ATG patients experienced, respectively, 10 and 6 rejection episodes within the first 3 months), the total number of 33B3.1 patients experiencing rejection throughout the follow-up was significantly higher than that of ATG (13 versus 6; P < 0.02). Immunological graft failure accounted for 2 pancreas and 2 kidney losses in the 33B3.1 group versus 1 in the ATG one (P = ns). The total number of infectious episodes was similar in both groups (21 versus 23). Two malignancies were observed in the ATG group (1 responsible for patient's death). One 33B3.1 patient died because of infectious pneumonia and 3 ATG patients died because of 2 cardiovascular diseases and 1 cancer. All patients had functioning grafts at the time of death. The 3-month and 36-month patient, pancreas, and kidney actuarial survival rates were, respectively, 100, 65, and 100%, and 95, 50, and 82% in the 33B3.1 group and 95, 80, and 90%, and 80, 70, and 80% in the ATG one (P = ns). These data suggest that, although a significantly higher rejection episode incidence was observed in patients treated with 33B3.1 monoclonal antibody as compared with ATG, similar long-term results can be obtained following primary cadaveric combined pancreas/kidney transplantation.

HILDA/LIF, G.CSF, IL-1 beta, IL-6, and TNF alpha production during acute rejection of human kidney allografts

HILDA/LIF, a recently described glycoprotein, has been characterized from supernatants of alloreactive T cell clones (CD4 and CD8) extracted from a human rejected kidney graft. This suggests a possible role for HILDA/LIF in the rejection process. In order to further investigate this possible role and the role of other cytokines in allograft rejection, we tested HILDA/LIF, G.CSF, IL-6, TNF alpha, and IL-1 beta in supernatants of cultured mononucleated cells from patients during rejection and from stable grafted patients. In addition, we also tested HILDA/LIF in urine of the same patients. No significant differences were directly observed in the production of HILDA/LIF, TNF alpha, and IL-1 beta in supernatants from mononucleated cells between rejecting and stable patients. However, when antibodies were used to block the TNF alpha and the IL-1 beta receptors, an increase of both cytokines was detected in cells from rejecting patients suggesting that an over-expression of both receptors and cytokines occurred during rejection. A significant increase was also observed for both G.CSF and IL-6 during the rejection compared to stable grafts. In addition, HILDA/LIF was detected in urine of patients during rejection and not in urine of stable patients, suggesting that this cytokine may indeed play a role in rejection.

Similar levels of granzyme A and perforin mRNA expression in rejected and tolerated heart allografts in donor-specific tolerance in rats

Congenic LEW.1W (RT1u) heart grafts in LEW.1A (RT1u) recipient rats are rejected within 15 +/- 6 days. Tolerance (> 100 days) can be induced by pretransplant donor-specific blood transfusions. In both cases, the graft is heavily infiltrated by recipient cells, and class I and class II molecules of the major histocompatibility complex are strongly expressed. Moreover, T lymphocytes extracted from both tolerated and rejected grafts are similarly cytotoxic in vitro against donor cells. However, it cannot be excluded that this cytotoxicity does not operate in vivo. To answer this important question, we have studied the expression of granzyme A and perforin mRNA expression, in situ, by Northern blotting. Our data show that the two corresponding mRNAs accumulate with the same kinetic and at the same level in rejected and tolerated grafts. These results strongly suggest that infiltrating cells are cytotoxic in vivo and that a "cellular rejection" does occur in the "tolerated" grafts. In addition, these findings show that cytotoxic T lymphocytes are not sufficient to impair graft survival and lead to a revaluation of the relevance, in general, terms of granzyme and perforin expression as a correlate of rejection.

[Kidney transplantation and HLA-DR compatibility evaluated by genomic analysis: one center study]

The actual effect of HLA-DR matching in renal transplantation remains controversial. Since DNA analysis has been shown to be more reliable than serological typing, a re-evaluation of the impact of DR-matching on graft prognosis is required. In this study, 224 cadaver kidney transplantations performed in our center were retrospectively matched according to Restriction Fragment Length Polymorphism DR incompatibilities and compared to prospective serological DR-matching. Transplant outcome was evaluated using graft survival, first rejection onset and rejection frequency. In 18.8% individuals, a discrepancy between serology and DNA typing for at least one antigen was noted. Serology particularly failed to type recipients (21.7%) and 43.2% of the total missed antigens were serologically "blank" or unidentified ("X") alleles. A graft survival rate of 100% after one year was observed for transplantations with no DNA DR mismatch (n = 31). Furthermore, there was a definite correlation between DNA matching and (i), the percentage of individuals with one or more than one acute rejection episode (18% and 41.8% at one year for O incompatibility and pooled 1 and 2 incompatibilities respectively, p < 0.05); (ii), the mean of acute rejection per individual (p < 0.001); and (iii), the rejection onset time (p < 0.01). No correlation between serological matching and the acute rejection episodes parameters was noted. Since HLA typing could be performed in less than 2 hrs using new molecular biology techniques, we conclude that prospective DNA typing should improve kidney transplantation outcome in the near future.

[Anti-cytokines and anti-cytokine receptors]

Cytokines play a key-role in the immune response. The best known of them is interleukin-2 and its specific receptors. Monoclonal antibodies directed against the interleukin-2 receptor have initially enabled this receptor to be characterized; then they served to confirm the major role played by this cytokine in immune responses, where it proved effective in many animal models such as allograft reaction, delayed hypersensitivity reaction and some experimental auto-immune diseases. These results have been confirmed in man, particularly in kidney transplantation (but also in bone marrow transplantation), and they encourage to develop new bioreagents (chimeral antibodies, "humanized" antibodies, fusion proteins). Some of these reagents are now undergoing evaluation in renal transplantation. The principles of these bioreagents, issued from molecular biology, can be applied to other cytokines involved in the immunopathological mechanisms of certain diseases such as, for example, IL-6 and its role in the development of myeloma. Data from immune intervention directed against other cytokines are, for the moment, preliminary, but many potential targets (IL-1, IL-4, TNF alpha, INF gamma) are emerging.