What Is Bare Lymphocyte (BLS) Syndrome?

BLS is an inherited condition of the immune system, known as a "primary immunodeficiency."

Children inherit the BLS gene from their parents. Both must carry the genetic mutation for BLS but may not have symptoms of the disease.

The body's immune system is responsible for fighting infections and anything it sees as foreign invaders to the body.

In BLS, the body has a shortage of immune proteins called major histocompatibility complex (MHC) class I and II proteins. MHC proteins attack bacteria or viruses that enter the body.

Doctors also call BLS MHC class II deficiency or HLA class I deficiency.

How Common Is BLS?

BLS is a rare disease.

Since BLS symptoms are like those of other childhood illnesses, doctors don't know how many people have the disease.

Bare Lymphocyte Syndrome Symptoms

BLS symptoms depending on how severe the disease is. Children may have symptoms before one year of age or not until later in childhood.

BLS symptoms may be longer-lasting and more severe than those of other childhood diseases.

Some symptoms of BLS are:

  • Respiratory infections that keep coming back, including sinus and lung infections.
  • Skin infections that don't respond well to treatment.
  • Chronic diarrhea.

Complications of BLS

Children with primary immune deficiencies like BLS are:

  • More prone than others to getting infections.
  • Slower to clear infections from their bodies.
  • Recurrent, severe lung infections that can cause permanent damage to other organs such as the lungs and liver. This, in turn, causes severe health problems into adulthood.

How Do You Diagnose Bare Lymphocyte Syndrome?

Doctors diagnose BLS through blood tests. Testing for certain immune markers in the blood lets us see how well the immune system is functioning.

Your child may also need a chest x-ray to see whether BLS has caused damage to the lungs.

We also offer genetic testing at UPMC Children’s Hospital of Pittsburgh of UPMC.

Bare Lymphocyte Syndrome Treatment

The goals of BLS treatment are to:

  • Control the symptoms of this disease.
  • Avoid infections.
  • Improve your child's quality of life.

Children with BLS may need aggressive treatment for any infections they have. If your child doesn't have any infections, your doctor might prescribe antibiotics to prevent them.

Your child needs to avoid live vaccines and may need IVIG therapy.

If BLS is causing severe health problems such as lung failure, your child may benefit from a:

  • Bone marrow transplant.
  • Cord blood transplant.
  • Or even a lung transplant.

The Hillman Center for Pediatric Transplant is the world’s only program that offers tandem lung and bone marrow transplants.

We also pioneered a reduced-intensity bone marrow transplant program. It helps reduce the negative effects a bone marrow or stem cell transplant has on the body's organs.

Because transplants are high-risk treatments, your child may need to remain on lifelong medication.

Paul Szabolcs, MD

Chief, Bone Marrow Transplantation and Cellular Therapies

Dr. Szabolcs is a pioneer in reduced-toxicity/intensity unrelated donor cord blood transplant for inborn errors of immunity. He's the first to prove the feasibility of sequential lung and bone marrow transplantation from the same unrelated deceased donor.

Your Child's BLS Consult and Care: What to Expect

If a doctor diagnosed your child with bare lymphocyte syndrome, we want you to know you're not alone. The Center for Rare Disease Therapy (CRDT) is here to help.

To make an appointment for your child or refer a patient for BLS care, contact us by:

Here’s what you can expect when you come to us for your child's first BLS consult.

What should I expect at my child's first visit for BLS?

You can expect your first visit to take from 4 to 6 hours.

Your child will receive a complete assessment from Paul Szabolcs, MD.

He will make or confirm a precise diagnosis and find out how much the disease has progressed.

We work as a team here at the center, so other experts might see your child during your visit.

These may include specialists in:

  • Genetic diseases.
  • Brain diseases.
  • Child development.
  • Hearing.
  • Physical therapy.

What are the next steps after my child's visit to the Center for Rare Disease Therapy?

Members of your child's BLS care team will talk with you about:

  • Likely next steps for your child.
  • Options for treating bare lymphocyte syndrome.
  • Ways to care for your child at home to help improve his or her quality of life.

If surgery might be an option for treating your child's BLS, we'll discuss all the details. We'll let you know how you and your child can prepare.

By the end of your visit, you will have a care plan tailored to your child’s needs. We'll also schedule a follow-up visit in 3 months.

You'll meet our nurse practitioner. You can call or video conference them with any concerns you have between now and your next appointment.

Before you leave, please feel free to ask us about your child's BLS diagnosis, treatment, or anything else .

How long will I need to wait for my child's BLS test results?

We’ll call you within 2 weeks to discuss the test results and next steps for your child's BLS care.

You can also access test on MyCHP. Our patient portal is free for Children's patients, parents, and guardians.

Partners in Your Child's BLS Care

When a child has a rare disease like bare lymphocyte syndrome, it affects the whole family.

At the Center for Rare Disease Therapy, we see each family member as our partners.

The best care approach happens when we merge our BLS expertise with your knowledge of what’s best for your child.

Center for Rare Disease Therapy patient storiesMeet Our Rare Disease Center Patients

Learn how others are finding help and hope for their child’s rare disease through the expertise at UPMC Children’s.

View Center for Rare Disease Therapy patient stories »

Contact Us About Your Child’s BLS

At the CRDT, every child diagnosed with a rare disease receives a tailored treatment plan and family-centered care.

For an appointment, consult, or referral, contact us:

We’ll be in touch within 2 business days.