T Cell Collection by Apheresis

What is T cell collection by apheresis?

T cell collection by apheresis is a nonsurgical procedure to remove T cells, a type of white blood cell, from your child’s blood.

What to expect

If your child is referred to the Apheresis Program for T cell collection, they will have an initial evaluation by a physician-nurse team in the Apheresis Unit. The apheresis team will already know about your child and her condition from your child’s treating physician.

Prior to the apheresis collection procedure, your child’s transplant staff and experts from the Apheresis Program will check to see if your child has adequate veins for the large needle generally used in stem cell collection.

Many young children have thin, fragile, and/or small veins that are difficult to access. In that case, your child will need a central venous catheter (CVC) or port placed in CHOP’s Interventional Radiology Unit or operating room. Your child will be sedated so he should not have any pain during catheter/port placement.

On the day of your child’s procedure, our team will greet you and your child when you arrive. You will be directed to a patient area that includes:

  • A reclining chair or bed for your child
  • A high-tech apheresis machine that will be customized for your child’s size and procedure
  • Room for you to sit with your child
  • A television to distract and entertain your child

Your child’s procedure will be overseen by board-certified apheresis physicians, experienced apheresis nurses and child life staff. One or more team members will be with your child at all times to provide comfort, answer questions, and ensure the procedure goes smoothly.

How is T cell collection by apheresis performed?

For T cell collection, your child’s blood will be withdrawn through a needle or catheter into a cell separator machine that separates the blood using a centrifuge. White blood cells containing stem cells are collected in a bag, while the rest of your child’s blood is returned to her through another vein or catheter. This procedure is called apheresis.

If your child has adequate veins for a large needle, an apheresis nurse will insert needles into the veins of both of your child’s arms to withdraw and return the blood. If your child has a central venous catheter (CVC) or port, blood will be withdrawn from one side, and returned to the other side.

Children who are especially small (weighing less than 25 Kg), or have anemia (low red blood cell count) will receive a blood transfusion with packed red blood cells (called blood prime) at the beginning of their T cell collection procedure.

In addition, all children will receive a small amount of blood thinning medication called citrate to prevent their blood from clotting during the procedure.   Citrate binds to calcium in the blood to lower your risk for clotting but may also cause low levels of calcium in the blood which can affect the heartbeat.  Extra calcium is given during the procedure, usually through an IV, the prevent side effects known as citrate toxicity.

The cycle of drawing and returning your child’s blood is done simultaneously, so your child’s circulating volume remains stable.

T cell collection may take three to six hours to complete.  T-cell collections are typically completed in one day, however there are cases in which a second day is required.

At the end of each procedure, the T cell product will be taken to the Cell and Gene Therapy Lab at CHOP. 


T cell collection by apheresis is a safe procedure, but side effects can occur.

Your child may experience:

  • Symptoms similar to regular blood donation, such as fatigue, nausea, vomiting, dizziness or fainting
  • Problems related to the anticoagulant, including sour taste in the mouth, tingling around the lips or fingers, muscle cramping or irregular heart beats
  • Bruising, numbness, pain or infection at the site of the needle stick or catheter insertion
  • Circulatory changes including low or fluctuating blood pressure during and immediately after the procedure
  • Reactions related to a blood transfusion (if needed), including itching, rash, hives, shortness of breath, back pain or fever

The procedure may lower your child’s platelet count.  The Apheresis physician will carefully monitor platelet counts and transfuse platelets as needed to prevent potential bleeding. 

Serious complications including abnormal heart rate, seizures and severe allergic reactions are extremely rare, but can occur.

If your child experiences any of these symptoms, please tell your child’s medical team.