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Primary Immune Deficiency

Primary immune deficiency is a chronic disease caused by genetic defect in the immune system. The immune system protects our bodies from germs such as bacteria, viruses and fungi that cause infection. People with PID have immune system that doesn’t work properly against these germs so they have infections that last long time and is hard to treat, or they suffered from frequent severe infections.

PID can be mild or severe, if your child has 2 or more from these signs, you should ask for medical attention.

  • 8 or more ear infections within 1 year.
  • 2 or more sinus infection within 1 year.
  • 2 or more lung infections within 1 year.
  • Failure of a baby to gain weight.
  • Oral thrush after age 1.
  • Need for IV antibiotics to clear infections.
  • 2 or more deep seated infections.
  • Deep skin or organs abscesses that keep coming back.
  • A family history of PID.
  • Serious infections with unusual pathogens. 

PID can be diagnosed by blood test. It is best to find out as soon as possible. Early detection and treatment can save life for a child. 

BLOOD TESTS FOR PID DIAGNOSIS 

CBC should be obtained to screen for T cell or phagocytic disorder. T cell disorders are characterized by lymphocytopenia. Lymphocyte count is age-dependent if the absolute lymphocyte count is 2 standard deviation below the mean. T cell disorder can be confirmed by lack or delay hypersensitivity skin test response to candida; mumps or tetanus in children older than 1 year and by lymphocyte subset analysis at any age. This test will screen for the number and percentage of T cells, B cells and natural killer cells. 

Phagocytic disorders are characterized by neutropenia and abnormalities in granules in neutrophils if count is less than 1500 per m3. PID should be suspected if Neutrophil count is normal then  granulocyte function tests can be performed. 

Serum immunoglobulin: Patients with B cell disorders have low serum immunoglobulin levels and decreased production of IG to vaccination. 

Complement testing: Complement disorders are screened by checking the components of the classic and alternative pathways. The classic pathway is checked with CH50 assay, if its normal then it means the child does not have significant complement deficiency, but if the result is abnormal, then the alternative pathway should be checked with AH50 or CH100 assay. 

Newborn Screening for SCID in newborns is recommended as early identification and treatment with stem cell transplantation which can prevent infant death. Screening involves detection of T cell receptor excision circles by polymerase chain reaction using newborn heel stick dried blood spot. T cell receptor excision circles are piece of DNA produce only by T-cell. 

CAUSES

  • B cell (antibody) deficiency
  • T cell deficiencies
  • Combined B and T cell deficiencies
  • Defective phagocytes
  • Complement deficiency

MANAGING INFECTIONS

Infections require rapid and aggressive treatment with antibiotics. Infections that don’t respond may require hospitalization and IV treatments. Some people need long term antibiotics to prevent infections.

TREATMENT TO BOOST THE IMMUNE SYSTEM

  • Immunoglobulin therapy for IG deficiency
  • Gamma interferon therapy to treat chronic granulomatous disease.
  • Growth factor for lack of white blood cells.

When the child has PID, there are certain vaccines which they should not have:

  • Oral polio
  • MMR vaccine
  • BCG vaccine
  • Varicella vaccine
  • Rotavirus vaccine
  • Yellow fever vaccine

STEM CELL TRANSPLANTATION

Stem Cell transplantation offers a permanent cure for several forms of life threatening immunodeficiency.

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