Donor Lymphocyte Infusion

• Donor Lymphocyte Infusion (DLI) is a treatment for cancer relapse after allogeneic stem cell transplant.
• It harnesses the donor’s immune cells to target and eliminate residual cancer cells in the recipient.
• The procedure involves collecting lymphocytes from the original stem cell donor and infusing them into the patient.
• A primary benefit is the graft-versus-leukemia effect, which can lead to disease remission.
• Potential side effects include graft-versus-host disease (GVHD) and myelosuppression.

What is Donor Lymphocyte Infusion (DLI)?

Donor Lymphocyte Infusion (DLI) is a medical procedure that involves the transfusion of T-lymphocytes and other immune cells from a healthy donor to a recipient, typically a patient who has previously undergone an allogeneic hematopoietic stem cell transplant (HSCT). The primary goal of DLI is to induce a “graft-versus-leukemia” (GVL) or “graft-versus-tumor” (GVT) effect, where the donor’s immune cells recognize and destroy residual cancer cells in the patient. This approach is particularly valuable for patients experiencing a relapse of their underlying hematological malignancy, such as leukemia or lymphoma, after an initial successful stem cell transplant. By leveraging the donor’s immune system, DLI aims to provide a potent anti-cancer effect without requiring further intensive chemotherapy or radiation, which can be highly toxic to patients who have already undergone extensive treatments.

The Donor Lymphocyte Infusion Procedure

The Donor lymphocyte infusion procedure typically begins with the collection of lymphocytes from the original stem cell donor. This is usually done through a process called apheresis, where the donor’s blood is passed through a machine that separates out the white blood cells (including lymphocytes) and returns the remaining blood components to the donor. The collected lymphocytes may then be processed, and in some cases, specific cell populations might be selected or depleted depending on the clinical strategy. Once prepared, these donor lymphocytes are infused intravenously into the patient, similar to a blood transfusion. The timing and dosage of the DLI are carefully determined by the medical team, taking into account factors such as the patient’s disease status, the extent of relapse, and the risk of potential complications. The procedure is generally performed in an outpatient setting, allowing patients to return home after the infusion, though close monitoring for side effects is essential.

Benefits and Potential Side Effects of DLI

The primary benefits of donor lymphocyte infusion stem from its ability to harness the donor’s immune system to combat residual or relapsed cancer cells. This graft-versus-leukemia (GVL) effect can lead to durable remissions in a significant proportion of patients, particularly those with certain types of leukemia like chronic myeloid leukemia (CML) or acute myeloid leukemia (AML). DLI offers a non-chemotherapeutic option for relapse, potentially sparing patients from the severe toxicities associated with further intensive chemotherapy. Clinical studies have shown that DLI can be highly effective in inducing remission, with success rates varying based on the type of malignancy and the timing of the infusion.

However, DLI is not without potential complications. The most significant of the Donor lymphocyte infusion side effects is graft-versus-host disease (GVHD). This occurs when the infused donor lymphocytes recognize the recipient’s healthy tissues as foreign and attack them. GVHD can range from mild to severe, affecting various organs such as the skin, liver, and gastrointestinal tract. Other potential side effects include:

• Myelosuppression: A decrease in bone marrow activity, leading to low blood cell counts, which can increase the risk of infection and bleeding.
• Infections: The patient’s immune system may be further suppressed, making them more vulnerable to viral, bacterial, or fungal infections.
• Cytokine release syndrome: A systemic inflammatory response that can cause fever, fatigue, and other flu-like symptoms.
• Pure red cell aplasia: A rare condition where the bone marrow stops producing red blood cells.

Careful patient selection, dose titration of lymphocytes, and vigilant monitoring are crucial to maximize the therapeutic benefits of DLI while minimizing its associated risks.