Immunodeficiencies: Phagocyte and complement dysfunction: Pathology review

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Immunodeficiencies: Phagocyte and complement dysfunction: Pathology review

Immune system


Immunodeficiencies: Phagocyte and complement dysfunction: Pathology review

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An 18-year-old girl is brought to the emergency room for evaluation of fever, headache, confusion and vomiting for two days. This morning she developed a rash on her lower extremities, prompting her college roommate to bring her to the emergency department. Past medical history includes recurrent pelvic inflammatory disease with Neisseria gonorrhoeae. The patient is sexually active with her boyfriend and uses condoms for contraception. Temperature is 40.2 C° (104.4 F°), pulse is 110/min, respirations are 29/min and blood pressure is 100/55 mmHg. Physical examination demonstrates a lethargic female with an erythematous, non-blanching petechial rash on the trunk and lower extremities.  The hips flex when the neck is flexed. Which of the following best describes the underlying pathophysiology of this patient’s clinical condition?  


Alyssa is a 3 week old newborn baby girl that’s brought to the clinic by her parents. They’re a bit concerned because they’ve noticed that Alyssa’s umbilical cord stump hasn’t fallen off yet.

On physical examination, you notice that the stump looks red and swollen, but there’s no pus. You decide to run a blood test, which reveals an increased level of neutrophils.

Finally, you perform flow cytometry, which shows that these neutrophils have reduced expression of CD18.

Next comes Eddie, a 2 year old boy who has a fever that won’t go away after 2 weeks. His parents also mention that he has frequent infections involving the respiratory tract, and he once also had an infection of the knee joint.

Upon physical examination, the first thing you notice is that Eddie has extremely light skin, hair, and eyes. Then, you find swollen lymph nodes all around the body, and you palpate an enlarged liver and spleen.

So again you run some blood tests, but now you find decreased white blood cells, especially neutrophils, and a prolonged bleeding time.

Finally, you do a peripheral and bone marrow smear, which shows abnormally large granules within the white blood cells and platelets.

Based on the initial presentation, both cases seem to have some form of immunodeficiency, meaning that their immune system's ability to fight pathogens is compromised.

Immunodeficiencies can be classified according to the component of the immune system that is defective.

In this video, we’ll be focusing on phagocyte dysfunction and complement disorders. Okay, let’s start with phagocyte dysfunction.

First we have leukocyte adhesion deficiency, which is an autosomal recessive disorder, meaning that an individual needs to inherit two copies of the mutated gene, one from each parent, to develop the condition.

Normally, when there’s an infection or inflammatory process, as well as for wound healing, chemical signals are released by cells in the affected area, to attract leukocytes such as phagocytes that are circulating in the blood, and this is called chemotaxis.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Defects in the Leukocyte Adhesion Cascade" Clinical Reviews in Allergy & Immunology (2009)
  4. "Chediak-Higashi syndrome" Current Opinion in Hematology (2008)
  5. "Features of Severe Periodontal Disease in a Teenager With Chédiak-Higashi Syndrome" Journal of Periodontology (2000)
  6. "A Rare Cause of Recurrent Oral Lesions: Chediak- Higashi Syndrome" Turkish Journal of Hematology (2014)
  7. "Chronic Granulomatous Disease: Report on a National Registry of 368 Patients" Medicine (2000)

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