Use of immunotoxins to induce immune tolerance to pancreatic islet transplantation

Abstract

The invention provides a method of treating diabetes in a subject, comprising administering to the diabetic subject an immunotoxin, thereby reducing the subject's T-cell population, and administering to the subject pancreatic islet cells from a donor. The immune tolerance inducing treatment regimen, used optionally with adjunct immunosuppressive agents, prevents pancreatic islet cell rejection while maintaining long term islet cell function following xenogeneic and allogeneic pancreatic islet cell transplantation. Thus, the methods of the present invention provide a means for treating diabetes, wherein the need for exogenous insulin or immunosuppressive agents is decreased or eliminated. Also provided is a method of inhibiting a rejection response of a transplant recipient, comprising administering an immunotoxin during the peritransplant period, thereby transiently reducing the number of T-cell lymphocytes and promoting long-term survival of the transplant.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of The Invention [0002] This invention generally relates to techniques for inducing immune tolerance using an immunotoxin. In particular, this invention relates to the use of immune tolerance inducing techniques with pancreatic islet transplantation, for the purpose of inhibiting rejection of the transplant. This invention further relates to the treatment of diabetes using immune tolerance inducing techniques in conjunction with pancreatic islet transplantation. [0003] 2. Background Art [0004] There are 16 million diabetics within the United States. Ninety percent of these have Type II diabetes, which is defined by hyperglycemia in the face of normal or elevated levels of circulating insulin. As Type II diabetes progresses, however, a decrease in circulating level of insulin may occur as the beta cells of the pancreatic islets produce and secrete less insulin. The mechanism of insulin resistance in Type II diabetes has not been elucidated,...

AI Technical Summary

Benefits of technology

[0014] The invention provides a method of treating diabetes in a subject, comprising administering to the diabetic subject an immunotoxin, thereby reducing the subject's T-cell population, and administering to the subject pancreatic islet cells from a donor. The method is effective for treating Type I or Type II diabetes. More specifically, the invention provides a short course immune tolerance inducing treatment regimen utilizing an anti-CD3 immunotoxin that, optionally with adjunct immunosuppressive agents, prevents pancreatic islet cell rejection while maintaining long term islet cell function following pancreatic islet cell transplantation. The invention further provides sufficient immune tolerance to pancreatic islet transplantation so that xenogeneic transplants are not rejected. Thus, the methods of the present invention provide a means for treating diabetes, wherein the need for exogenous insulin or immunosuppressive agents is eliminated.

Problems solved by technology

The mechanism of insulin resistance in Type II diabetes has not been elucidated, and the condition has proved to be difficult to treat and is currently the leading cause of renal failure in this country.

Nonetheless, even with insulin replacement therapy, euglycemia is not achieved and at least one half of the Type I population cannot achieve sufficient control to prevent the complications of retinopathy, vasculopathy, and renal deterioration (71,72).

In fact clinical tests of islet transplantation have been limited largely to type I diabetics and patients who have previously undergone total pancreatectomy (75).

Even treatment of Type I diabetes with pancreatic islet allografts, however, has not been effective in freeing most patients from exogenous insulin injections (71,73).

The problem has been that the immunosuppressive reagents required to inhibit allograft rejection can severely compromise transplanted islet cell function (71).

As with many transplant procedures, securing viable allogeneic grafts can be difficult.

In addition, long term immunosuppression can be problematic.

In addition to the cost, these agents, because of their non-specific effects, have considerable side effects, including compromising islet cell function and increasing susceptibility to infection.

However, thymic tolerance has never been reported in large animals, and its relevance to tolerance in humans in unknown.

However, this approach has proved difficult to adapt to live primates (e.g. monkeys; humans).

ALS and / or radiation render the host susceptible to disease or side-effects and / or are insufficiently effective.

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