Introduction

Today, kidney transplantation is considered the best treatment option for many patients with end-stage kidney disease. However, not all patients can easily receive a kidney from their intended donor. In some cases, the recipient’s immune system has antibodies against the donor, which can lead to rapid rejection of the transplanted kidney.

To overcome this challenge, transplant specialists use a group of treatments known as desensitization therapies. These approaches make it possible to perform successful kidney transplantation even when immunological incompatibilities exist between donor and recipient.

Why Is Desensitization Important in Kidney Transplantation?

The immune system is designed to recognize and eliminate foreign substances. Unfortunately, after transplantation, the new kidney may also be recognized as foreign and become the target of an immune attack.

Three major situations typically require desensitization:

1. ABO-Incompatible Kidney Transplantation

Examples include:

  • Recipient with blood group O and donor with blood group B
  • Recipient with blood group O and donor with blood group A

In these situations, the recipient naturally possesses antibodies against the donor’s blood group antigens.

2. Presence of Donor-Specific Antibodies (DSA)

Patients may develop donor-specific antibodies due to previous pregnancies, blood transfusions, or prior organ transplants.

3. Positive Crossmatch

A positive crossmatch indicates that the recipient’s serum reacts against donor cells. Without appropriate treatment, this can result in severe antibody-mediated rejection.

Plasmapheresis: The First Line of Defense

Plasmapheresis is one of the most important desensitization procedures in kidney transplantation.

During plasmapheresis:

  • Blood is removed from the patient.
  • Blood cells are separated and preserved.
  • Plasma containing harmful antibodies is removed.
  • Replacement fluids such as albumin or donor plasma are infused.

In simple terms, plasmapheresis acts like removing a stockpile of missiles before they can attack the transplanted kidney.

Benefits of Plasmapheresis

  • Rapid reduction of circulating antibodies
  • Reduction of Anti-A and Anti-B antibody titers
  • Reduction of donor-specific antibodies (DSA)
  • Preparation of the patient for transplantation

Limitations of Plasmapheresis

Plasmapheresis only removes antibodies that are already circulating in the bloodstream. It does not eliminate the cells responsible for producing new antibodies.

For this reason, multiple sessions are often required, and plasmapheresis is usually combined with additional therapies.

IVIG: Modulating the Immune System

Intravenous Immunoglobulin (IVIG) is prepared from the plasma of thousands of healthy donors.

Although it may seem counterintuitive, IVIG is not given to increase harmful antibodies. Instead, its primary role is to regulate and calm the immune system.

How Does IVIG Work?

IVIG helps by:

  • Reducing excessive immune activity
  • Inhibiting complement activation
  • Reducing antibody rebound after plasmapheresis
  • Lowering the risk of transplant rejection

Why Is IVIG Given After Plasmapheresis?

Plasmapheresis removes a large portion of the body’s immunoglobulins. IVIG helps restore immune balance while reducing the risk of infections and immune overactivity.

In many kidney transplant desensitization protocols, IVIG is administered after each plasmapheresis session or at the completion of treatment.

Rituximab: Preventing the Production of New Antibodies

Rituximab is one of the most important medications used in desensitization protocols.

Rituximab targets CD20-positive B lymphocytes.

B cells are the precursor cells that eventually develop into antibody-producing plasma cells.

How Does Rituximab Work?

While plasmapheresis removes existing antibodies, rituximab helps prevent the formation of new antibodies by eliminating B cells.

For this reason, rituximab is typically administered two to four weeks before kidney transplantation.

Benefits of Rituximab

  • Reduces antibody rebound
  • Improves outcomes in ABO-incompatible transplantation
  • Decreases the risk of antibody-mediated rejection

Limitations of Rituximab

Rituximab does not directly eliminate mature plasma cells. Therefore, antibodies that have already been produced may continue to circulate in the body.

Bortezomib: Targeting the Antibody Factory

Bortezomib represents a more advanced desensitization strategy.

Unlike rituximab, which targets B cells, bortezomib directly targets plasma cells—the primary factories responsible for antibody production.

Which Patients May Benefit from Bortezomib?

  • Patients with very high DSA levels
  • Patients with resistant positive crossmatches
  • Highly sensitized patients with elevated cPRA
  • High-risk transplant candidates
  • Patients with previous transplant rejection

Benefits of Bortezomib

  • Powerful reduction of antibody production
  • Useful in highly sensitized patients
  • May enable transplantation in otherwise difficult cases

Potential Side Effects

  • Peripheral neuropathy
  • Low platelet counts
  • Reduced white blood cell counts
  • Increased risk of infection

Because of these risks, bortezomib is generally reserved for selected high-risk patients.

How These Therapies Work Together

In many transplant centers, these treatments are combined to achieve optimal desensitization.

A typical protocol may include:

  1. Rituximab administered several weeks before transplantation
  2. Multiple sessions of plasmapheresis
  3. IVIG administration following plasmapheresis
  4. Bortezomib in highly sensitized or difficult cases

This combination strategy:

  • Removes existing antibodies
  • Prevents the formation of new antibodies
  • Reduces the risk of rejection
  • Improves transplant success rates

The Future of Desensitization in Kidney Transplantation

Desensitization has transformed modern kidney transplantation. Patients who were once considered unsuitable candidates due to blood group incompatibility or high antibody levels can now successfully receive a life-saving transplant.

As transplant medicine continues to advance, improved desensitization protocols and newer therapies are expected to further expand access to kidney transplantation while improving long-term graft survival and patient outcomes.

Conclusion

Desensitization has become one of the most significant breakthroughs in modern transplant medicine. Plasmapheresis removes circulating antibodies, IVIG regulates the immune response, rituximab prevents the formation of new antibodies, and bortezomib targets the plasma cells responsible for antibody production.

When used together, these therapies significantly increase the likelihood of successful kidney transplantation, even in highly sensitized patients or those with donor incompatibilities.