Which amino acid can be used as fuel by immune cells, similar to glucose?

• A. Glutamine
• B. Arginine
• C. Leucine
• D. Valine

Answer: (A)

Immune cells, especially when activated, rely on glutamine as a key fuel to support energy production and biosynthesis. Glutamine is converted to glutamate and then to alpha-ketoglutarate, feeding the TCA cycle (a process called glutaminolysis). This helps generate ATP and provides carbon and nitrogen for making nucleotides, amino acids, and lipids needed for rapid cell proliferation and function. Glutamine is also important for maintaining redox balance and supporting antioxidant defenses.

Among the options, glutamine best fits as the amino acid used as fuel by immune cells, similar to glucose. Arginine is crucial for nitric oxide production and polyamine synthesis rather than primarily serving as a fuel. Leucine and valine are branched-chain amino acids mainly used for protein synthesis and energy in other tissues, not the primary energy source for activated immune cells.