What is Donor Lymphocyte Infusion (DLI)?

A DLI or Donor Lymphocyte Infusion is a form of cellular therapy used after an allogeneic stem cell transplant for improving the immunity of the recipient..

The immune system comprises different types of white blood cells, including lymphocytes, that can modulate the response of the immune system against infections and cancer..

DLI involves the infusion of lymphocytes, particularly T-cells, extracted from the stem cell donor into the body of the recipient. These donor cells can enhance the patient’s immune response and reduce the risk of relapse.
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How does DLI work?

DLI consists of donor T-cells which are infused into the body of the recipient after stem cell transplant. The top-up of donor T-cells can help boost the patient’s immune system and improve the ability of the donor graft to identify and attack any residual cancer cells..

Chemotherapy might be administered to the patient before the DLI to reduce the number of cancer cells further and improve the results of the treatment. Following the donor lymphocyte infusion procedure, the patient is continually monitored to assess the response.
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Who needs DLI?

There are two primary reasons why a DLI can be beneficial for a patient who has had a stem cell transplant. These include:
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1. Mixed chimerism
   Chimerism is measured after stem cell transplantation regularly. It tells us how much of the patient’s bone marrow is from the donor. Chimerism should be as close to 100% of the donor’s bone marrow as possible for ensuring the success of the stem cell transplant.
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   If the chimerism level becomes low consistently, it suggests that not enough of the recipient’s bone marrow is from the donor. This could be an indication of a higher risk of relapse or graft failure.
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   It may occur when the donor’s stem cells fail to multiply and grow in the recipient’s bone marrow after the transplantation.
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   A DLI is recommended in such cases to boost the donor immune response and increase the chimerism to the acceptable level.
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   However, it is important to note that not all patients need to have 100% donor chimerism. A lower level of donor chimerism may be considered acceptable if it’s stable. Our transplant doctor will assess your donor chimerism and help you to understand your post-transplant results.
   

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2. Relapse
   Relapse after stem cell transplantation can sometimes be managed with Donor Lymphocyte Infusions. DLI is generally more effective in the treatment of low-level relapse that is picked up early using MRD (Minimal Residual Disease) testing.
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   The immune response induced by DLI can help fight cancer cells at the time of relapse. But as the DLI effect is often weak when given on its own, in patients with more aggressive relapse, the DLI is usually given after the patient receives a bout of treatment (chemotherapy or targeted therapy) to clear the bulk of the disease first.
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   It’s important to note that a DLI may not be the best treatment for relapse in all cases. In addition, relapse can also occur with or without reduced chimerism. If the risk of relapse after transplant is high, a sequence of DLI may be planned before the transplantation and infused at time intervals after the transplant.
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How is DLI collected?

DLI can be obtained during stem cell collection from the donor for transplantation. If enough of these cells are present in the collection, DLI can be extracted and frozen and stored for later use..

If there are not enough cells available, the stem cell collection needs to be repeated. In such cases, the donor is contacted for the collection when the patient needs a DLI..

The procedure for DLI collection is simpler compared to that of stem cell collection. It does not involve the administration of growth factor injections as a high level of lymphocytes are usually present in the blood.
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How is DLI given?

In most cases, the procedure can be performed as a day procedure. During the procedure, DLI is thawed and administered to the patient. It is given as an infusion and takes about 30 minutes. DLI is usually infused in increasing doses over a period of a few weeks to months. The transplant team will determine the frequency and doses.

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What are the side effects of DLI?

Most patients do not experience any severe side effects while receiving DLI. In some cases, they may develop a reaction or experience an unpleasant smell due to the preservative called ‘DMSO’ that is added to DLI when it is frozen..

Graft versus host disease (GVHD) is a common side effect of DLI. It may occur in the initial few weeks after the infusion. GVHD is a condition wherein the graft or the donor cells may proliferate too aggressively and attack the host cells in the patient’s body. Infusion of DLI in smaller but increasing doses over a period of a few weeks can help in controlling this risk..

However, a moderate GVHD response is considered a good sign as it indicates that DLI has induced the desired immune response. Balancing GVHD to produce the desired effect without causing severe side effects is the key to the successful outcome of DLI. However, the absence of GVHD does not mean that DLI has failed to evoke the desired immune response.

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FAQs