Complementary data about the inhibitory effects of intravenous immunoglobulins in vitro and in vivo

New treatments for acute humoral rejection of kidney allografts

Acute antibody-mediated rejection (acute humoral rejection; AHR) of organ allografts usually presents as severe dysfunction with a high risk of allograft loss. Peritubular capillary complement C4d deposition with renal dysfunction, associated with circulating donor-specific anti-human leukocyte antigen alloantibodies, is diagnostic of AHR in kidney allografts. Removal of alloantibodies with suppression of antibody production and rejection reversal is now possible. Therapeutic strategies that include combinations of plasmapheresis (or immunoadsorption), tacrolimus, mycophenolate mofetil and/or intravenous immunoglobulins, as well as rituximab or splenectomy, have been recently used to successfully treat AHR. However, the optimal protocol to treat AHR still remains to be defined. Anti-CD20+ monoclonal antibody therapy (rituximab) aiming at depleting B cells and suppressing antibody production has been used as rescue therapy in some episodes of steroid- and antilymphocyte-resistant humoral rejection. Plasmapheresis and/or intravenous polyclonal immunoglobulin, as well as rituximab, have also been used to successfully desensitize selected high-immunological risk patients in anticipation of a previously cross-match positive (or ABO incompatible) kidney transplantation. In the near future, the possible role of new specific anti-B-cell approaches or, possibly, of new anti-T-cell activation approaches using selective agents such as belatacept should be assessed to further refine the present treatment of humoral rejection.

Successful renal transplant outcome after intravenous gamma-globulin treatment of a highly sensitized pediatric recipient

Approximately 10% of patients on the renal transplant (Tx) cadaver waiting list have high (> 20%) panel-reactive antibody (PRA) levels to human leukocyte antigens (HLA). Intravenous gamma-globulin (IVIG) has been shown to reduce anti-HLA cytotoxic antibody levels through an anti-idiotypic antibody-blocking effect. We report a successful renal Tx outcome in a 7-yr-old-girl with high PRA levels owing to a failed renal Tx who experienced a significant reduction in PRA levels (from 96% to 0%) concomitant with IVIG therapy. IVIG was infused weekly (500 mg/kg/week) for 3 consecutive weeks every 12 weeks. Thirty-four months after starting IVIG therapy, the PRA activity dropped to zero and IVIG was stopped. Then IVIG therapy was resumed after 8 months due to a rebound in PRA activity to 52%. Forty-four months after starting IVIG therapy, the patient was cross-matched with a cadaver donor who shared three antigens with the first living donor. The cross-match was positive with the recipient's sera obtained prior to IVIG therapy and negative with the recipient's sera obtained post-IVIG therapy. A successful cadaver renal Tx was performed using anti-thymocyte globulin (ATGAM) induction therapy and a tacrolimus-based immunosuppression protocol. IVIG was given (1 g/kg) prior to Tx and at day 4 post-operatively. A single mild acute rejection episode occurred 10 days post-transplantation that responded to pulse methylprednisolone therapy and an increase in the tacrolimus oral dose. We conclude that a prolonged course of IVIG infusions, without immunosuppressive medications or plasmapheresis, is likely to have been beneficial in modulating the immune response in this highly sensitized recipient. Randomized multicenter trials are required to define the role of IVIG in this specific population.

A randomized and prospective study comparing treatment with high-dose intravenous immunoglobulin with monoclonal antibodies for rescue of kidney grafts with steroid-resistant rejection

BACKGROUND

The aim of this study was to compare the effectiveness of intravenous immunoglobulin (IVIg) versus monoclonal anti-CD3 as a treatment for steroid-resistant rejections. From January 1995 to June 1997, 30 patients were analyzed. They were randomized into two groups. Resistant rejections were diagnosed by core biopsy. Group A received 500 mg/ kg/day IVIg (Sandoglobulin) for 7 consecutive days, whereas group B received 5 mg/day of OKT3 for 14 consecutive days. Daily T cell CD3+ peripheral count was performed for 14 days for group B. The immunosuppression was similar for both groups. Cyclosporine was stopped during both treatments.

METHODS

Demographic factors, HLA mismatch, creatinine levels before and after treatment, and the incidence of rejections after treatment (up to 1 month) were taken into account for this study.

RESULTS

Data from different samples were compared using Fisher's exact test. Graft and patient survival were analyzed using the Kaplan-Meier method. The were no significant differences found in age, graft origin, HLA mismatch, or time of follow-up until the episode of rejection. Success was achieved for 11 (73.3%) of 15 of group A and 13 (86.6%) of 15 of group B (P=0.79). Creatinine levels before and after treatment were as follows: A, 2.99+/-1.30 mg/dl and 2.1+/-0.70 mg/dl versus B, 3.1+/-1.1 mg/dl and 2.5+/-0.8 mg/dl. Besides, we did not observe differences in the creatinine 1 month after treatment (A: 2.35+/-0.78 mg/dl; B: 2.51+/-1.10 mg/dl; P=0.66) nor in the third month (A: 1.83+/-0.58 mg/dl; B: 2.30+/-0.89 mg/dl; P=0.24). The incidence of rejections after treatment was 5 (46%) of 11 for group A and 9 (75%) of 12 for group B (P=0.4). The patient survival rates 2 years after treatment were 87 and 92% for A and B groups, respectively. Graft survival was identical (80% in both groups).

CONCLUSION

Should the favorable result presented in this report be confirmed in larger number of patients, IVIg could become the preferable choice of rejection treatment for steroid-resistant rejection because of a complete absence of the unwanted side effects commonly associated with OKT3.

Plasmapheresis and intravenous immune globulin provides effective rescue therapy for refractory humoral rejection and allows kidneys to be successfully transplanted into cross-match-positive recipients

BACKGROUND

Hyperacute rejection (HAR) and acute humoral rejection (AHR) remain recalcitrant conditions without effective treatments, and usually result in graft loss. Plasmapheresis (PP) has been shown to remove HLA- specific antibody (Ab) in many different clinical settings. Intravenous gamma globulin (IVIG) has been used to suppress alloantibody and modulate immune responses. Our hypothesis was that a combination of PP and IVIG could effectively and durably remove donor-specific, anti-HLA antibody (Ab), rescuing patients with established AHR and preemptively desensitizing recipients who had positive crossmatches with a potential live donor.

METHODS

The study patients consisted of seven live donor kidney transplant recipients who experienced AHR and had donor-specific Ab (DSA) for one or more mismatched donor HLA antigens. The patients segregated into two groups: three patients were treated for established AHR (rescue group) and four cross-match-positive patients received therapy before transplantation (preemptive group).

RESULTS

Using PP/IVIG we have successfully reversed established AHR in three patients. Four patients who were cross-match-positive (3 by flow cytometry and 1 by cytotoxic assay) and had DSA before treatment underwent successful renal transplantation utilizing their live donor. The overall mean creatinine for both treatment groups is 1.4+/-0.8 with a mean follow up of 58+/-40 weeks (range 17-116 weeks).

CONCLUSIONS

In this study, we present seven patients for whom the combined therapies of PP/IVIG were successful in reversing AHR mediated by Ab specific for donor HLA antigens. Furthermore, this protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity (AHG-CDC) cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.