Chemically, a cytokine is categorized as a:

AIIMS CRE, SNO-2024

Applied Nutrition & Dietetics

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

Cytokines are defined as a broad category of small, soluble proteins, peptides, or glycoproteins, typically with a molecular weight of less than 25 kDa.
Their chemical structure is a chain of amino acids (a polypeptide), which distinguishes them from lipids, steroids, or carbohydrates.
They function as signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.
Key examples include interleukins (ILs), interferons (IFNs), and chemokines, all of which are protein-based.

Option A: Carbohydrates are biological molecules consisting of carbon, hydrogen, and oxygen atoms, primarily functioning as energy sources or structural components. Cytokines are made of amino acids.
Option C: Steroid hormones are a class of lipids derived from cholesterol. They have a distinct four-ring carbon structure and are not proteins.
Option D: Long-chain fatty acids are components of lipids (fats and oils). They are carboxylic acids with a long aliphatic chain and are not related to the polypeptide structure of cytokines.

Visual 1: Diagram: A cytokine molecule (a small protein) being released from one cell and binding to a specific receptor on a target cell, triggering an intracellular signal. This illustrates their role in cell signaling.
Visual 2: Table: Major types of cytokines (Interleukins, Interferons, TNFs, Chemokines) and their primary functions in the immune system.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Chemical nature of cytokines as background academic context rather than a clinical decision trigger.
Cytokines are central to the inflammatory process. Elevated levels of pro-inflammatory cytokines like TNF-α and IL-6 are hallmarks of many inflammatory diseases, such as rheumatoid arthritis.
Many modern therapies for autoimmune diseases are 'biologics' that specifically target and inhibit cytokines (e.g., anti-TNF drugs) or their receptors to reduce inflammation.
A 'cytokine storm' is a life-threatening systemic inflammatory response caused by the rapid, uncontrolled release of large amounts of cytokines. This can occur in severe infections like sepsis or COVID-19, leading to widespread tissue damage and organ failure.

How to Approach the Question

First, identify the core term in the question: 'cytokine'.
Next, note the keyword 'chemically', which asks for the basic biochemical classification of the molecule.
Systematically evaluate the options based on fundamental biochemical categories: carbohydrates (sugars), proteins (amino acid chains), steroids (a type of lipid), and fatty acids (another type of lipid).
Recall or deduce the function of cytokines. They are signaling molecules in the immune system, a role commonly filled by proteins or peptides.
Match the function and known properties of cytokines to the correct chemical class. Cytokines are well-known to be small proteins, making this the correct choice.

Concept Tested & Keywords

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