What is a donor lymphocyte infusion?

A donor lymphocyte infusion (DLI) is the infusion of lymphocytes, specifically T cells, from your donor.

T cells are a type of lymphocyte that can cause an immune response. A DLI is used after a sibling or unrelated stem cell transplant.

When is a DLI used?

There are two main reasons why a DLI would be used:

Mixed chimerism

After a stem cell transplant, your chimerism will be measured on a regular basis. It tells us how much of your bone marrow is from the donor and should be as near to 100% donor as possible. If the chimerism level is consistently low or drops, it means not enough is from your donor and there is a risk of relapse or graft failure (when your donor’s cells fail to develop and grow properly). A DLI is given to cause an immune response which can push the chimerism back up to an acceptable level.

It’s important to remember:

• Not all patients will have 100% donor chimerism and that is fine if it’s stable.
• Your chimerism will be monitored for a period before the decision to have a DLI is made.
• A drop in chimerism does not mean you have relapsed.

Relapse

Relapse after a stem cell transplant can be treated with a DLI. If the relapse is low level and picked up early in a test for minimal residual disease (MRD), the immune response caused by a DLI can fight the disease and help put you into remission. If relapse is picked up on a bone marrow test or in the blood and there is higher level of disease, chemotherapy will be used first followed by a DLI to help put you into remission.

It’s important to remember:

• A DLI is not always possible as a treatment for relapse.
• Disease relapse can occur with or without a drop in chimerism.

In some cases, if a disease has a higher risk of relapse after transplant, a DLI can be planned in the pre-transplant phase to be given after the transplant. This might be done irrespective of chimerism or relapse but as an extra preventative measure for relapse. This should be discussed with you prior to the transplant.

How is a DLI collected?

When the donor’s stem cells are being collected, if there is enough within the collection a DLI can be removed, frozen and stored. Sometimes there isn’t enough, and all the collection must be used for the transplant. In this situation, if you need a DLI, your donor will be contacted and asked to donate.

A DLI is easier to collect than stem cells, injections are not needed as high levels of lymphocytes are always present in the blood and can be easily collected. However, the donor will still need to agree and have a medical before going ahead.

How is a DLI given?

A date will be discussed with you and, in most cases, the DLI can be given as an outpatient. If chemotherapy is given beforehand as an inpatient, then the DLI will also be given while you are an inpatient. The DLI will be thawed and given to you through a syringe as it is given in much smaller volumes than stem cells. The DLI is normally given in increasing doses over a period of weeks or sometimes months, but this and the dose will be determined by your transplant team.

What are the side effects?

It’s rare to experience side effects whilst receiving a DLI. Occasionally, there is a reaction and a smell from the preservative called ‘DMSO’ which is added when the DLI is frozen. A nurse will be with you throughout the whole infusion and you will be observed for a short time after.

The main side effect is graft versus host disease (GvHD) and this can happen in the weeks following the infusion. Although a side effect, GvHD is the response you want as it suggests the DLI has caused an immune response. The key is to balance GvHD by not causing too much of a reaction, but enough to give the desired effect. Giving the DLI in increasing doses over a period of weeks is a way of controlling the risk.

It’s important to remember:

• If you do not get GvHD, that does not mean the DLI has not worked – a response can be achieved without any side effects.

Recovery

This will vary depending on the experience of GvHD. Follow up in clinics might increase initially to monitor for symptoms and response, and to decide if another DLI is needed. If the response is achieved and any GvHD resolved, recovery after transplant should continue to be the same as prior to the DLI.

Why wouldn’t a DLI be given?

Every patient is different and the decision to give a DLI will be decided by the transplant team. These are just some reasons why a DLI wouldn’t be a treatment choice, but you should always discuss treatment with the transplant consultant.

• When a second transplant is the best treatment option – a second transplant will only be considered in the case of relapse or graft failure. There are several factors that will decide if this is the best option, such as the level of relapse/graft failure, time from transplant, age and fitness. This will be discussed with you by the transplant team.

• When you have already had significant acute GvHD – if significant acute GvHD has been experienced, which means the donor cells from the stem cell transplant have caused a good immune response, but the chimerism has still dropped or relapse has occurred, then giving a DLI to try and cause more GvHD is unlikely to work. This should be discussed with the transplant team, as having low levels of acute GvHD could still mean that a DLI is an option.

• When you are having ongoing treatment for chronic graft versus host disease (cGvHD) – giving a DLI when cGvHD is ongoing and being treated can cause a worsening of symptoms and acute GvHD. As above, if GvHD has already been experienced it is unlikely that a DLI would work.