science

Nasal-associated lymphoid tissue

Nasal-associated lymphoid tissue is a science 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 Nasal-associated lymphoid tissue rather than just read about it. In short: Nasal- or nasopharynx- associated lymphoid tissue (NALT) represents immune system of nasal mucosa and is a part of mucosa-associated lymphoid tissue (MALT) in mammals. It protects body from airborne viruses and other infectious agents.

Key takeaways

Nasal-associated lymphoid tissue belongs to science; place it in that map before memorising details.
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Connect Nasal-associated lymphoid tissue to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nasal-associated lymphoid tissue from memory before moving on to harder problems.

Reference excerpt

Nasal- or nasopharynx- associated lymphoid tissue (NALT) represents immune system of nasal mucosa and is a part of mucosa-associated lymphoid tissue (MALT) in mammals. It protects body from airborne viruses and other infectious agents. In humans, NALT is considered analogous to Waldeyer's ring.

Structure

NALT in mice is localized on cartilaginous soft palate of upper jaw, it is situated bilaterally on the posterior side of the palate. It consists mainly of lymphocytes, T cell and B cell enriched zones, follicle-associated epithelium (FAE) with epithelial M cells and some erythrocytes. M cells are typical for antigen intake from mucosa. In some areas of NALT, there are lymphatic vessels and HEVs (high endothelial venule). Dendritic cells and macrophages are also present. NALT contains about same amount of T cells and B cells. The T-cell population contains about 3–4 times more CD4+ T cells than CD8+ T cells. Most of T cells are with αβ T cell receptor (TCR) and only few are with γδ TCR. CD4+ T cells are in naive state, marked by high expression of CD45RB. B cells are mostly in unswitched state, with sIgM+ IgD+ phenotype.

Development Formation of NALT starts early after birth, it is not present during embrygenesis or in newborn mice. First signs of NALT (HEV with associated lymphocytes) occurs one week after birth, but full formation is established after 5–8 weeks. In contrast to Peyer's patches and lymph nodes, NALT formation is independent of IL-7R, LT-βR and ROR-γ signalling. It requires Id2 gene, which induce genesis of CD3−CD4+CD45+ cells. These cells accumulates on the site of NALT after birth and induce NALT formation.

Function NALT in mice has strategic position for incoming pathogens and it is the first site of recognition and elimination of inhaled pathogens. It has a key role in inducing mucosal and systemic immune response. NALT is inductive site of MALT similarly to Peyer's patches in a small intestine. After intranasal immunization or pathogen recognition, lymphocytes in NALT proliferate and differentiate. They start to produce cytokines, such as IFN-γ, type I interferons, IL-2, IL-4, IL-5, IL-6 or IL-10 (amount depend on used immunizating agent or adjuvans). B cells go through isotype switching and produce antigen-specific IgM, IgG and mainly IgA. Activated B cells can migrate through body to respiratory and genito-uritary tract, because they express chemokine receptors CCR10 and α4β1-integrin. Memory T and B cells are established and last for long time after immunization.

Vaccination Intranasal (i.n.) immunization or vaccination is an effective way to stimulate respiratory immune system. This way of immunization can provoke both the cell-mediated and humoral immune responses and is capable of stimulating both the mucosal and systemic immune systems. A dose of i.n. administered antigen can be much smaller than of oral administered antigen, because antigens are not exposed to digestive enzymes. Thus, it would be a suitable way of vaccination against airborne viruses and bacteria. In 1997, nasal-spray vaccine containing inactivated influenza virus with nLT (heat-labile enterotoxin) as adjuvants was used in Switzerland, but it had to be withdrawn from the market, because it caused Bell's palsy in some patients. Thus, scientists are looking for more suitable and safe adjuvants, for expamle, Masafumi Yamamoto et al. in 1998 on mice model proved safe and efficient i.n. vaccination against Streptococcus pneumoniae and in 2002 also against influenza virus.

References

Worked examples

Example 1 — a first encounter with Nasal-associated lymphoid tissue

Start with the simplest possible case. Write down what Nasal-associated lymphoid tissue claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Nasal-associated lymphoid tissue 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 Nasal-associated lymphoid tissue 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 Nasal-associated lymphoid tissue

In research: Nasal-associated lymphoid tissue appears in science 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 Nasal-associated lymphoid tissue 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: Nasal-associated lymphoid tissue is common in secondary-school and first-year university syllabi. It links to neighbouring topics Immune system, so understanding it makes those chapters shorter.
In everyday life: Look for Nasal-associated lymphoid tissue 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 Nasal-associated lymphoid tissue in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nasal-associated lymphoid tissue 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.
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Frequently asked questions

What is Nasal-associated lymphoid tissue in simple terms?

Why does Nasal-associated lymphoid tissue matter?

Because it connects several science 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 Nasal-associated lymphoid tissue?

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 Nasal-associated lymphoid tissue.