mathematics

Leukocyte adhesion deficiency

Leukocyte adhesion deficiency is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Leukocyte adhesion deficiency rather than just read about it. In short: Leukocyte adhesion deficiency (LAD) is a rare autosomal recessive disorder characterized by immunodeficiency resulting in recurrent infections. LAD is currently divided into three subtypes: LAD1, LAD2, and the recently described LAD3, also known as LAD-1/variant.

Key takeaways

Leukocyte adhesion deficiency belongs to mathematics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Leukocyte adhesion deficiency to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Leukocyte adhesion deficiency from memory before moving on to harder problems.

Reference excerpt

Leukocyte adhesion deficiency (LAD) is a rare autosomal recessive disorder characterized by immunodeficiency resulting in recurrent infections. LAD is currently divided into three subtypes: LAD1, LAD2, and the recently described LAD3, also known as LAD-1/variant. In LAD3, the immune defects are supplemented by a Glanzmann thrombasthenia-like bleeding tendency.

Signs and symptoms LAD was first recognized as a distinct clinical entity in the 1970s. The classic descriptions of LAD included recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. The adhesion defects result in poor leukocyte chemotaxis, particularly neutrophil, inability to form pus and neutrophilia. Individuals with LAD suffer from bacterial infections beginning in the neonatal period. Infections such as omphalitis, pneumonia, gingivitis, and peritonitis are common and often life-threatening due to the infant's inability to properly destroy the invading pathogens. These individuals do not form abscesses because granulocytes cannot migrate to the sites of infection.

Cause

Types of leukocyte adhesion deficiency include LAD1, LAD2, and LAD3. LAD1 is the most common.

Patients with LAD1 have an inherited molecular defect that causes a deficiency of the β-2 integrin subunit, also called CD18, which is encoded by the ITGB2 gene found on chromosome 21. This subunit is involved in the formation of the β-2 integrins (LFA-1, integrin alphaXbeta2/CR4/p150,95, and Mac-1/CR3) by dimerization with different CD11 subunits. Mutations in the ITGB2 gene lead to absent, reduced, or aberrant CD18 protein expression, causing a lack of expression in the leukocyte membrane of the β-2 integrins. The main function of these proteins is to allow neutrophils to make their way out of the blood stream and into the infected tissues by adhering to different ligands expressed by the endothelium, e.g. ICAM-1. In LAD-I patients, neutrophils cannot extravasate and fight against bacteria in tissues. The bacteria can then proliferate, leading to symptomatic infection, which can spread unimpeded and cause serious injury to important tissues.

Diagnosis Typically, diagnosis involves several preliminary tests of immune function, including basic evaluation of the humoral immune system and the cell-mediated immune system. A WBC differential will reveal extremely elevated levels of neutrophils (on the order of 6–10x normal) because they are unable to leave the blood vessels. In the case of LAD-I, specific diagnosis is done by flow cytometry. This technique will reveal absent or reduced CD18 expression in the leukocyte membrane. Recently, prenatal diagnosis systems has been established, allowing an early detection of the disease. LAD-II diagnosis includes the study of different glycosylated forms of the transferrin protein. In LAD-III, as platelet function is also affected, this could be used to differentiate it from the other types.

Treatment Although patients can receive intensive antibiotherapy and even granulocyte transfusions from healthy donors, the only current curative therapy is the hematopoietic stem cell transplant. However, progress has been made in gene therapy, an active area of research. Both foamyviral and lentiviral vectors expressing the human ITGB2 gene under the control of different promoters have been developed and have been tested so far in preclinical LAD-I models (such as CD18-deficient mice and canine leukocyte adhesion deficiency-affected dogs).

Prognosis A 2009 study reported results from 36 children who had received a stem cell transplant. At the time of follow-up (median time 62 months), the survival rate was 75%.

Epidemiology LAD is a rare disease, with an estimated prevalence of one in 100,000 births, with no described racial or ethnic predilection. The most common type is LAD1.

See also Congenital disorder of glycosylation Leukocyte adhesion cascade

References

External links

Worked examples

Example 1 — a first encounter with Leukocyte adhesion deficiency

Start with the simplest possible case. Write down what Leukocyte adhesion deficiency claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Leukocyte adhesion deficiency before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Leukocyte adhesion deficiency ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Leukocyte adhesion deficiency

In research: Leukocyte adhesion deficiency appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Leukocyte adhesion deficiency in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Leukocyte adhesion deficiency is common in secondary-school and first-year university syllabi. It links to neighbouring topics Autosomal recessive disorders, Congenital defects of phagocyte number, function, or both, Hematology, so understanding it makes those chapters shorter.
In everyday life: Look for Leukocyte adhesion deficiency outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Leukocyte adhesion deficiency in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Leukocyte adhesion deficiency means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Leukocyte adhesion deficiency out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Leukocyte adhesion deficiency in simple terms?

Why does Leukocyte adhesion deficiency matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Leukocyte adhesion deficiency?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Leukocyte adhesion deficiency.