Extracorporeal Photopheresis (ECP)

What is extracorporeal photopheresis?

Extracorporeal photopheresis (ECP) is a cutting-edge, nonsurgical procedure to treat graft-versus-host disease (GVHD), a complication of bone marrow and stem cell transplants and other autoimmune disorders in children. ECP is also used to treat solid organ transplant rejection.

In this procedure, your child’s blood is drawn and the white blood cells are separated from the rest of the blood. The white blood cells are then combined with a photoactive drug, exposed to ultraviolet light to “activate” the medicine, and finally reinfused back into your child.

This therapy is designed to stop a type of white blood cell (called lymphocytes) from attacking your child’s body from within. Lymphocytes are part of the body’s immune system. If your child has received an organ, tissue or stem cell transplant, and his body sees the new transplanted cells as a threat, the lymphocytes may try to reject the transplanted cells.

If your child’s body is rejecting healthy cells — because of a transplant, GVHD or other reason — your child’s doctor may recommend extracorporeal photopheresis as a treatment or additional therapy for his long-term care.

For many children, extracorporeal photopheresis interrupts the body’s immune system defense mechanism – effectively halting disease symptoms. This lets them live as normally as possible given their condition.

Extracorporeal photopheresis is a series of treatments repeated over several months during the course of your child’s care.

Who needs extracorporeal photopheresis?

Extracorporeal photopheresis can be performed on children and adults, and may be used alone or in combination with other treatments.

It is used to treat:

  • Graft-versus-host disease
  • Organ rejection after solid organ transplant

At The Children’s Hospital of Philadelphia, our pediatric Apheresis Program has performed approximately 350 extracorporeal photopheresis procedures during the past two years.

What to expect

If your child is referred to the Apheresis Program for extracorporeal photopheresis, she 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.

On the day of your child’s procedure, the Apheresis 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
  • Chairs for you to sit with your child
  • A television to distract and entertain your child

As a special precaution for patients undergoing extracorporeal photopheresis, your child will be directed to one of two smaller rooms in the Apheresis Unit where the overhead lights are dimmed and the shades are drawn. This additional caution is needed because your child will be exposed to 8-methoxypsoralen, a drug that will make your child’s body more sensitive to light for up to 24 hours after the procedure.

Your child’s procedure will be overseen by board-certified physicians, and experienced 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 extracorporeal photopheresis performed?

For extracorporeal photopheresis, your child’s blood will be withdrawn by a needle or catheter into a cell separator machine. In most cases, your child will have a double lumen central venous catheter (CVC) or port to remove his blood. The CVC or port will be placed in CHOP’s Interventional Radiology Unit or in the operating room. Your child will be sedated so he should not have any pain during catheter/port placement.

In some cases, your child’s veins may be adequate to have the procedure performed using his arm veins.  If so, a clinician will insert a needle into both of your child’s arms: A large needle is inserted into a vein in one of your child’s arms to withdraw the blood; a small needle is inserted into a vein in the other arm to return the blood. Topical anesthetic can be used to numb your child’s skin where the IVs will be inserted.

Children who are small 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 extracorporeal photopheresis procedure.

In addition, all children will receive a small amount of blood thinning medications called anticoagulants — either citrate or heparin — to prevent their blood from clotting during the procedure. The apheresis physician will determine which anticoagulant, or a combination of the two, your child will receive based on his condition and lab tests.

Once your child has been prepared, the apheresis team will begin drawing your child’s blood from the peripheral vein, CVC or port and sending it into a cell separator machine. The machine separates the white blood cells from the other parts of the blood (red blood cells, plasma and platelets) by spinning the blood in a centrifuge-like bowl. White blood cells are collected in a bag, while the rest of your child’s blood is returned to him through another vein or catheter.

The cycle of drawing and returning your child’s blood is done slowly, so your child is never missing more than a few ounces of blood at a time.

Once your child’s white blood cell collection is complete, the bag containing the blood cells is injected with 8-methoxypsoralen (8-MOP), a light-sensitive drug that only becomes “active” when exposed to ultra violet A (UVA) light. The bag is then exposed to UVA light, making all of the collected blood “photoactivated” (known as treated cells).

The treated white blood cells are then immediately returned to your child intravenously. These cells stimulate an immune response in your child’s body, essentially distracting the body from attacking healthy cells and preventing disease progression.

The time for extracorporeal photopheresis varies from patient to patient. In general, the treatment takes 2-3½ hours. In many cases, photopheresis is a 3-day process per week, but children are not required to stay overnight in the Hospital.


Extracorporeal photopheresis is a safe procedure, but side effects can occur.

Your child may experience:

  • Symptoms similar to regular blood donation, such as light headedness, nausea, vomiting, dizziness or fainting.
  • Circulatory changes including fluctuating blood pressure ranging from low to high during and immediately after the procedure. 
  • Shortness of breath, coughing or raised blood pressure due to extra-treated white blood cells that he received towards the end of the treatment. 
  • Adverse effects of 8-MOP, which makes your child more sensitive to sunlight and UV light for 24 hours after treatment. Your child should avoid sunlight as much as possible, even indirect sunlight coming through a window, wear sunscreen with 15 SPF or greater (indoors and outdoors), and wear full coverage sunglasses and clothing with UVA-protection.
  • Pain, swelling or bruising at the site of peripheral IV insertion.
  • Complications of the central venous line, such as infection or mechanical malfunction.
  • Reactions related to the anticoagulant:
    • If your child received citrate, he may experience chills, tingling around the lips or fingers, a sour taste in the mouth, muscle cramps in the legs or irregular heartbeats.
    • If your child received heparin, he may experience bruising or bleeding.
  • Reactions related to a blood transfusion (if needed), including itching, rash, hives, shortness of breath, back pain or fever.

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