Effect of immunosuppressants on OKT3 associated T cell activation: clinical implications

Temporal changes of cytokines and nitric oxide products in urine from renal transplant patients

BACKGROUND

Acute rejection and urinary tract infection (UTI) both increase nitric oxide synthase (NOS) activity in urine from renal transplant patients. Also, with rejection, a regulatory interplay between nitric oxide (NO) and cytokines has been suggested. Thus, measurement of the temporal changes of NOS products and cytokines in urine will provide a strategy for the diagnosis of acute rejection and for its differentiation from UTI.

METHODS

Soluble interleukins (ILs) and NOS-related products, cyclic GMP (cGMP), nitrate, and nitrite were measured in 192 urine samples consecutively collected from 13 patients within the first three months of transplantation. Sixty-seven additional urine specimens were collected randomly from 24 patients for follow-up analysis of the nitrate test.

RESULTS

Among patients who experienced rejection, the percentage (%) binding of IL-2 increased within the first five days (P = 0.0004) after transplantation and one to five days prior to the clinical diagnosis (dx) of rejection (P = 0.02). Tumor necrosis factor-alpha, IL-6, and IL-8 increased at the time of rejection dx (P < or = 0.01). With UTI, IL-2 (P = 0.01) decreased one to five days prior to dx, and IL-10 (P = 0.003) increased one to five days after dx. Although cGMP and nitrate are dependent variables, cGMP increased (P < or =0.0009) with both rejection and UTI, and nitrate increased (P = 0.0001) with rejection and decreased (P = 0.0001) with UTI. Prior to formal dx (1 to 5 days), urine nitrate clearly differentiated rejection (3004 to 7451 micromol/L) from UTI (90 to 885 micromol/L) and controls (1059 to 3235 micromol/L). The additional 67 urines demonstrated that the sensitivity of the nitrate test for rejection and UTI was 100%.

CONCLUSIONS

In renal transplant patients, specific temporal changes in urine cytokine levels do occur with acute rejection and UTI, but urine nitrate levels are the most precise at differentiating rejection from UTI.

Immuno-activation with anti-CD3 and recombinant human IL-2 in HIV-1-infected patients on potent antiretroviral therapy

BACKGROUND

A stable reservoir of latently infected, resting CD4 T cells has been demonstrated in HIV-1-infected patients despite prolonged antiretroviral treatment. This is a major barrier for the eradication of HIV by antiretroviral agents alone. Activation of these cells in the presence of antiretroviral therapy might be a strategy to increase the turnover rate of this reservoir.

METHODS

Three HIV-1-positive patients on potent antiretroviral therapy, in whom plasma viremia had been suppressed to below 5 copies/ml for at least 26 weeks, were treated with a combination of OKT3 (days 1-5) and recombinant human IL-2 (days 2 6).

RESULTS

The side-effects were fever, headache, nausea, diarrhea, and in one of the patients transient renal failure and seizures. The regimen resulted in profound T cell activation. In one patient plasma HIV-1 RNA transiently increased with a peak at 1500 copies/ml. In the other two patients plasma HIV-1 RNA levels remained below the detection limit, but HIV-1 RNA levels in the lymph nodes increased two- to threefold. All patients developed antibodies against OKT3.

CONCLUSION

OKT3/IL-2 resulted in T cell activation and proliferation, and could stimulate HIV replication in patients having achieved prolonged suppression of plasma viremia. OKT3/IL-2 therapy was toxic and rapidly induced antibodies against OKT3.

High-dose glucocorticosteroids increase the procoagulant effects of OKT3

The use of OKT3 as prophylaxis in renal transplantation carries an increased risk of intragraft thrombosis, which is related to the systemic activation of the coagulation system that consistently occurs after the first dose of OKT3. As only a few patients develop thrombosis after OKT3 therapy, we searched for possible additional risk factor by comparing the demographic and clinical parameters of the 13 patients who developed thrombosis in our institution to those of 218 patients who did not. Multivariate analysis showed a relationship between the dose of methylprednisolone (mPDS) given before the first OKT3 injection and the risk of thrombosis: 6 out of 42 patients (14%) who received high (30 mg/kg) mPDS experienced a thrombotic event, as compared to 7 out of the 189 patients (3.7%) who received < or = 8 mg/kg of mPDS (P < 0.01). This led us to study the effects of mPDS on the procoagulant activity induced by OKT3 on peripheral blood mononuclear cells (PBMC) in vitro. The procoagulant activity of unstimulated PBMC (mean +/- SEM: 0.6 +/- 0.1 mU/ml) reached 3.0 +/- 0.7 mU/ml after OKT3 stimulation (P = 0.0062) and further increased to 7.4 +/- 2.0 mU/ml when PBMC were first preincubated overnight with mPDS before OKT3 stimulation (P = 0.018 as compared to OKT3 alone). This process involved the tissue factor/factor VII pathway, as shown by increased membrane expression of tissue factor on monocytes as well as by a marked reduction of the induced procoagulant activity when the clotting assay was performed with factor VII-deficient plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibodies in renal transplantation: a review

OKT3 is the first anti-CD3 monoclonal antibody available for treatment in humans. Over the last few years it has proven to be a very powerful immunosuppressive agent in renal transplantation. Clinical studies have shown that OKT3 is superior to high-dose steroids as first-line treatment for acute renal allograft rejection. Furthermore, it is comparable to antithymocyte globulin (ATG) in treating steroid-resistant rejection and is also effective as rescue treatment in ATG- and antilymphocyte globulin-(ALG-) resistant rejection. Despite its excellent rejection-reversal rate, OKT3 treatment is followed by a substantial percentage of re-rejections, most of which respond well to steroids. In the early post-transplantation period, a prophylactic course of OKT3 is very effective in preventing acute rejections, and in this respect it is probably equivalent to ATG. Indirect evidence exists that a prophylactic course of OKT3 may be beneficial in immunologically high-risk patients and in patients with delayed graft function. However, more clinical studies are required to answer the question whether OKT3 should be given as induction treatment, as first-line treatment, or as rescue treatment. To answer this question, the side effects of OKT3 should also be taken into account. First-dose-related side effects, although frequent and disturbing, are usually transient and seldom life-threatening, provided overhydration has been corrected and steroids have been given before the first administration. These side effects are attributed to the release of cytokines as a result of T-cell activation or lysis. After exposure of patients to OKT3 an increased incidence of infections and malignancies has been reported. However, it is not yet clear whether this is due to OKT3 as such, or whether it merely reflects the total burden of immunosuppression. Xeno-sensitization represents an important limitation to OKT3 treatment, although a second or third course can still be effective in patients with low antibody titers. The precise immunosuppressive mechanism of anti-CD3 monoclonal antibodies is yet unknown. Monitoring of patients treated with OKT3 revealed CD3 and/or T-cell antigen receptor depletion and immunological incompetence of remaining T cells. More clinical data are required to establish the correct dose and duration of OKT3 treatment. In conclusion, OKT3 is a powerful immunosuppressive agent but its real value in renal transplantation remains to be determined. A practical approach may be to reserve it for the treatment of steroid-resistant rejections.(ABSTRACT TRUNCATED AT 400 WORDS)

OKT3 first-dose reaction: association with T cell subsets and cytokine release

Use of the monoclonal antibody OKT3 to prevent or treat allograft rejection has become commonplace. Its administration is often complicated by serious side effects, usually occurring within one to two hours after OKT3 is given, and is termed first-dose reaction. The mechanism underlying these signs and symptoms is poorly defined, but may be related to cytokine release. Twenty-three kidney or kidney/pancreas transplant recipients received OKT3 as treatment of acute rejection. Signs and symptoms occurring after the first dose were observed and quantitated prospectively, and a reaction score was calculated. Blood was drawn immediately before, and at 2 and 24 hours after the first dose of OKT3 for determination of interleukin-2 (IL2), interferon-gamma (IFN gamma), and tumor necrosis factor-alpha (TNF alpha) levels, and flow cytometric analysis of T cell subsets. Two groups were defined based on severity of first-dose reaction. Group 1 patients (N = 11) had very mild reactions (reaction score less than or equal to 3); Group 2 patients (N = 12) had more severe reactions (score greater than or equal to 5). All patients demonstrated a significant rise in serum TNF alpha from baseline to two hours after OKT3 (9 +/- 3 pg/ml to 378 +/- 54 pg/ml, P less than 0.0001), and there was significant correlation between reaction scores and two-hour TNF alpha levels (P = 0.005). Group 2 patients had higher TNF alpha levels at two hours than did Group 1 patients (484 +/- 75 pg/ml vs. 263 +/- 62 pg/ml, P = 0.04). Levels of IL2 and IFN gamma were not elevated at any sampling time.(ABSTRACT TRUNCATED AT 250 WORDS)