White blood cells are a key part of the immune system. They help the body fight off germs like bacteria and viruses. When your child doesn’t have enough white blood cells — also known as leukopenia — their body may have a harder time fighting infections.

There are different kinds of white blood cells, and each plays a special role:

• Neutrophils fight bacteria and fungi
• Lymphocytes fight viruses and make antibodies
• Monocytes help break down germs and damaged cells
• Eosinophils and basophils help with allergic reactions and fight parasites

A low white blood cell count can happen for many reasons. Sometimes, the body doesn’t make enough white blood cells. Other times, the body destroys them too quickly or they get stuck in the bone marrow.

Your child’s care team will do tests to find out what’s causing the problem and create a plan to treat it.

A low white blood cell count can be a sign of a blood cancer or bone marrow disorder. It may also just mean your child is recovering from an infection. It’s not always serious, but it can be.

Our team is here to help you understand what your child’s low white blood cell count means. We’ll figure out how to treat the health issue causing it.

Inherited Immune System Conditions

Inherited conditions are present at birth. Immune system conditions can make it hard for the body to fight germs. Some also cause low numbers of certain white blood cells.

• Severe combined immunodeficiency (SCID): A serious condition that affects both T cells and B cells. This disease process is also known as the "boy in the bubble" syndrome. Living in a normal environment can cause fatal infections in these children.
• Common variable immunodeficiency (CVID): Causes low antibody levels and sometimes low white blood cells. Kids with CVID have difficulty fighting disease, which can lead to recurring illnesses. The disease may become evident anytime between infancy and adulthood.
• X-linked agammaglobulinemia (XLA): The body doesn’t make mature B cells, which make antibodies. As a result, the child's body is unable to fight off bacterial and some viral infections. Only affects people with one X chromosome.
• DiGeorge syndrome: Affects the development of the immune system, especially T cells. It can also affect the parathyroid gland and cause heart defects or cleft lip or palate.
• Specific antibody deficiencies: The body has trouble making certain antibodies. People who have this disorder often have trouble fighting off chest and sinus infections, specifically.
• Autoimmune lymphoproliferative syndrome (ALPS): An inherited disorder. It causes an unusually high number of blood cells to collect in the lymph nodes, liver and spleen, which causes swelling.

We care for these conditions through the primary immunodeficiency program, the Kids with Immune Dysregulation Disorders (KIDDS) program and our bone marrow transplant team. Our main goal is to find and accurately diagnose these disorders as early as possible. This is critical in cases of serious immunodeficiency. We then provide you and your family with all the latest treatment options.

DNA Repair Conditions

Some rare diseases affect how cells fix damage to their DNA while healing. This can lead to problems with the immune system and low white blood cell counts. It's often seen in children who suffer from diseases that cause accelerated aging.

These include:

• Ataxia-telangiectasia: This rare condition causes trouble with balance and movement. It also causes a higher risk of infections and certain cancers.
• Nijmegen breakage syndrome: Kids with this condition are often small for their age and have learning challenges. They get frequent infections because their immune system doesn’t work well.
• LIG4 deficiency: This rare disorder affects how the body repairs cells. It also slows healing and raises the risk of infection.

Neutropenia Syndromes

Neutropenia means your child has too few neutrophils, a type of white blood cell that fights infection. These conditions can cause neutropenia from birth, in cycles or over time.

• Severe congenital neutropenia (SCN): A condition from birth that causes very low neutrophil levels. Kostmann syndrome is a type of SCN.
• Cyclic neutropenia: When neutrophil levels rise and fall in regular cycles.
• Chronic benign neutropenia: A mild condition that usually doesn’t cause serious problems. It can show up as abnormal white blood cell test results.
• Shwachman-Diamond syndrome: Affects bone marrow and digestion. It often causes low neutrophils.
• WHIM syndrome (myelokathexis): White blood cells get stuck in the bone marrow and don’t reach the blood.

Immune Conditions That Attack White Blood Cells

Sometimes, the immune system makes a mistake and attacks the body’s own white blood cells.

• Autoimmune neutropenia: The body attacks its own neutrophils.
• Neonatal alloimmune neutropenia: While in the womb, the mother’s antibodies attack the baby’s white blood cells.
• Evans syndrome: The body attacks more than one type of blood cell, including white blood cells.

Treatment for low white blood cell counts depends on your child’s age, overall health and specific diagnosis.

Some children need short-term support, while others need long-term care. We’ll work closely with your family to build a care plan. These treatments will support your child’s immune system and reduce the risk of infection.

We offer a full range of therapies — from medicine to advanced treatments. We also take part in research to find new ways to care for children with rare immune and blood cell conditions.

Infection Prevention

Treatment can help protect your child from infections. These boost the immune system and lower the risk of serious illness.

• Vaccines: Protect against infections your child may be more likely to get.
• Immunoglobulin therapy: Delivers infection-fighting antibodies.

Medicines

Some medicines help the body make more white blood cells or help those cells work better. Others, like antibiotics, help fight off infection. We offer pain medicines or other therapies if needed.

Bone Marrow Transplant

For certain serious conditions, a bone marrow transplant may be needed. It is an aggressive treatment but offers a potential cure. It’s used for some severe conditions, such as SCID or congenital neutropenia.

At Children’s Wisconsin, we care for many families facing the same questions and fears. You’ll find expert care, compassionate staff and a team that listens to you. From the moment you arrive, you’ll know you’re in the right place.

We know it can feel overwhelming to come to the hospital, especially when your child is being tested or treated for a serious immune condition. At Children’s Wisconsin, we do everything we can to make your visit easier, more comfortable and more informative for your whole family.

Your First Appointment

At your first visit, your child will meet with a pediatric specialist who understands white blood cell disorders. We’ll talk with you about your child’s health history, symptoms, family history and any recent test results. Our goal is to understand what’s going on and start building a care plan tailored to your child.

We may also:

• Do a physical exam
• Order lab tests or imaging
• Talk about genetic testing, if needed
• Answer all your questions

You’ll leave with next steps, follow-up plans and the direct contact information for someone on your care team.

Advanced Testing and Diagnosis

Children’s Wisconsin is home to one of the most advanced immune system testing labs in the country, the CIRL. If we recommend additional testing, we’ll explain what it is, why it matters and how to prepare.

We offer:

• Detailed immune cell counts
• Antibody testing
• Genetic testing for rare immune disorders
• Specialized tests that are only available at top pediatric centers

Some results come back the same day. Others may take a few weeks. We’ll keep you updated every step of the way.

A Team-Based Approach to Care

If your child has a confirmed low white blood cell disorder, we’ll bring in other experts as needed. Your child’s care team may include:

• Hematologists (blood specialists)
• Immunologists
• Infectious disease doctors
• Rheumatologists
• Genetic counselors
• Nurses, pharmacists and social workers

We’ll meet together to review your child’s condition and create a care plan that fits their unique needs.

Follow-up and Ongoing Support

Many children with white blood cell disorders need long-term follow-up to stay healthy. We’ll schedule regular check-ins to:

• Track blood counts
• Prevent infections
• Adjust medications or treatments
• Support your child’s growth and development

We’ll also connect you with family resources, support programs and financial counselors if needed.