Health Library · Process & Patient Journey

Leukapheresis for CAR-T: What Patients Should Expect

Practical patient guide · Updated 2026

Leukapheresis is the first practical step in making an autologous CAR-T product. It is the procedure used to collect the patient’s own T cells so they can be sent to the manufacturing laboratory, genetically engineered, expanded and later returned as the CAR-T therapy.

For many patients this is the first time they hear the word “leukapheresis.” Understanding what happens during the procedure, how long it takes, and what side effects are possible helps reduce anxiety and allows better preparation.

What is leukapheresis?

Leukapheresis is a type of apheresis in which white blood cells (including T cells) are separated from the rest of the blood. Blood is drawn from the patient, passed through a specialized machine that separates the desired cell layer, and the remaining blood components are returned to the patient.

In the CAR-T setting the goal is to collect enough healthy T cells to serve as the starting material for manufacturing. The collected cells are not the final treatment; they are the raw material that will later become the engineered CAR-T product.

When does leukapheresis happen in the CAR-T pathway?

Leukapheresis is performed only after the medical team has confirmed that the patient is a suitable candidate and that manufacturing can be planned. It usually occurs days to a short time before the cells are expected to enter the production process. After collection, the cells are transported under controlled conditions to the manufacturing laboratory.

How the procedure is performed

Vascular access

Most patients need good venous access. This may be achieved through:

• Peripheral veins in both arms (one line for drawing blood, one for return), or
• A temporary central venous catheter if peripheral veins are not adequate

The team assesses veins in advance and decides which approach is safest for the individual patient.

The collection itself

Once access is established, the patient is connected to the apheresis machine. Blood circulates through the device, white cells are collected into a bag, and the processed blood is returned. The procedure is performed while the patient is awake and resting in a reclining chair or bed. Staff monitor vital signs and the machine throughout.

Duration

A typical CAR-T leukapheresis session lasts several hours (commonly in the range of 3–6 hours, sometimes longer depending on the cell yield needed and the patient’s blood counts). Some centers complete collection in a single day; occasionally a second session is required if the first yield is insufficient.

How to prepare

• Follow any instructions about medications, especially blood thinners or other agents that may affect the procedure.
• Stay well hydrated in the days before collection unless advised otherwise.
• Eat a normal meal beforehand unless the center gives different guidance.
• Wear comfortable clothing with sleeves that can be rolled up easily.
• Arrange transport home; many patients feel tired afterward.
• Bring something to pass the time (music, book, tablet), as the procedure is lengthy but usually not painful.

The clinical team will also review recent blood counts and may check electrolytes, especially calcium, because the anticoagulant used in the machine can temporarily lower available calcium.

Common sensations and side effects

Leukapheresis is generally well tolerated, but some temporary effects are common:

• Tingling around the mouth, fingers or toes — related to temporary changes in calcium levels from the citrate anticoagulant. This is usually managed by slowing the procedure or giving calcium.
• Chills or feeling cold — blood is outside the body for a short time; blankets are typically provided.
• Fatigue — many patients feel tired during or after the long session.
• Low blood pressure or light-headedness — occasional; monitored and managed by the team.
• Bruising or discomfort at the needle or catheter site

Serious complications are uncommon when the procedure is performed by experienced teams, but any apheresis carries small risks related to vascular access, bleeding, clotting or allergic reactions. The staff are trained to recognize and treat these events.

After the procedure

Most patients can go home the same day once they are stable. Advice commonly includes:

• Rest for the remainder of the day
• Drink fluids unless restricted for medical reasons
• Watch the access site for bleeding or swelling
• Report unusual symptoms (severe dizziness, prolonged bleeding, chest discomfort, significant numbness) to the care team

The collected cells are processed and sent to the manufacturing laboratory. From this point the patient enters the waiting period while the CAR-T product is produced and tested. Bridging therapy may be given during this interval if the disease needs interim control.

Questions patients often ask

Is leukapheresis the same as dialysis?
No. Both use a machine to process blood, but the purpose and the filters are different. Leukapheresis specifically targets white blood cells for collection.

Will I lose a lot of blood?
The red cells and plasma are largely returned to you. The volume of white cells removed is relatively small.

Can the procedure fail?
Sometimes the cell yield is lower than needed. In that case the team may repeat the collection or discuss alternatives. This is why pre-collection assessment is important.

Does it hurt?
The placement of needles or a catheter can cause brief discomfort. The collection itself is not typically painful.

Key points to remember

• Leukapheresis is the cell-collection step that supplies the starting material for autologous CAR-T manufacturing.
• It is usually an outpatient or day-procedure lasting several hours.
• Temporary tingling, fatigue and feeling cold are the most common side effects and are generally manageable.
• Good preparation and experienced staff reduce risk and improve the chance of an adequate cell yield.
• After collection, the manufacturing and quality-control phase begins; infusion occurs only after the product is released.

For the full sequence of steps from evaluation to infusion, see How Does the CAR-T Cell Therapy Process Work Step by Step?