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What is Immune Deficiency?

The immune system is composed of multiple types of cells, tissues, organs and proteins. The primary function of the immune system is to distinguish between self and non-self (foreign). When something that is non-self, or foreign, is encountered, (such as bacteria, virus or fungi) the immune system attacks it to help prevent infection or other injury. Immune deficiency conditions (also referred to as immunodeficiency) occur when the immune system is unable to do its job, either partially or entirely.

When a baby is born, they are protected from infections by immune cells transmitted to them by their mothers. Within the first six months, though, babies’ immune systems develop and begin to assume responsibility for fighting off infections. But sometimes, babies have immune deficiencies and they don't have the ability to fight off routine infections on their own.

The symptoms of immune deficiency depend on what part of the immune system is affected and can range from mild to life-threatening.


Primary Immune Deficiencies

Immune deficiency conditions can be present at birth as a result of genetic defects in any of the components of the immune system. Such conditions are called primary immune deficiencies. Immune deficiencies can also be caused as a result of infections, cancer treatments, or medications. There are more than 150 types of primary immune deficiencies.

Immune deficiency conditions weaken the body’s ability to fight off infection. Symptoms include:

  • Frequent infections
  • Severe infections
  • Non-respondent infections (don’t respond to treatment)
  • Recurrent infections

Repeated infections in children can interfere with nutrition, leading to failure to gain weight (also known as failure to thrive), weight loss, slow growth, and slow development. Chronic sinusitis and bronchitis are also commonly associated with immune deficiency conditions.  Recurrent infections in infancy and childhood may be the first indication of a primary immune deficiency.

Although reducing exposure to infectious agents and treating infections are important in managing immune deficiency conditions, several primary immune deficiencies can now be treated through replacement of defective immune system components. As a result of advances in treatment, children with potentially fatal primary immune deficiencies are now living into adulthood.


Life-Threatening Immune Deficiency

These disorders lead to severe abnormalities of the immune system with reduced or malfunctioning T- and B-lymphocytes, the specialized white blood cells made in the bone marrow to fight infection. When the immune system doesn't function properly, it can be difficult or impossible for it to battle viruses, bacteria, and fungi that cause infections.

One example of a life-threatening immune deficiency is Severe Combined Immune Deficiency (SCID).  SCID and other severe immune deficiencies can be successfully treated if identified early. Otherwise, they can be fatal within the first year of life.  

Through the addition of Severe Combined Immune Deficiency (SCID) to the core panel of 29 genetic disorders on the national Recommended Uniform Screening Panel, the diagnosis process will initiate before the child has experiences an infection increasing their ability to survive.

Children with severe immune deficiency should not be immunized with live viruses — like the chickenpox (varicella), rotavirus, or measles, mumps, and rubella (MMR) vaccines — because they lack the normal defense of antibodies to the viruses. Introducing a virus, even a weakened vaccine virus, can be dangerous. Doctors may also administer an infusion of intravenous immune globulin (IVIG) to help the body fight infection.

The most effective treatment for immune deficiencies like SCID is Cord Blood or Bone Marrow transplantation.


Cord Blood / Bone Marrow Transplant

Cord blood comes from a newborn baby's umbilical cord and placenta containing lifesaving cells.  Bone marrow is the spongy material found in the center of large bones. Bone marrow produces special cells with unique functions:

  • Red blood cells carry oxygen through the body
  • White blood cells fight off infection
  • Platelets help the blood to clot

During a Cord Blood or Bone Marrow Transplant, the collected cells are introduced into the body in the hopes that the new cells will rebuild the immune system.  To provide the best chances for success, a transplant is usually done using the cord blood or bone marrow of a sibling. However, a parent's bone marrow might also be acceptable. Some children do not have family members who are suitable donors — in such cases, doctors may use cells from an unrelated banked cord blood or adult donor through the National Marrow Donor Program. The likelihood of a good outcome also is higher if the transplant is done early, within the first few months of life, if possible. 

Key steps in the life saving transplant journey:

  • Preparation: Days leading to the transplant day.  Preparatory medication, usually chemotherapy, is administered to remove the damaged immune system
  • Day 0 / Transplant:   The donor cells are injected via IV into the recipient.
  • Day +1 thru +20: Meticulous monitoring of infections while the immune system is rebuilt
  • Day +21 thru +28: White blood cells reactivate and the new immune system begins to take hold
  • Ongoing: From there forward the immune system is engaged in protecting the body from potential infections as it grows.  Follow-up visits to the doctor are critical to ensure proper care and progress.
To learn more about the topics covered in this section, we encourage you to visit:
http://primaryimmune.org/
http://marrow.org/

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