Which pair of serum proteins are negative acute-phase reactants?

• A. Albumin and Transferrin
• B. C-Reactive Protein and Fibrinogen
• C. Retinol Binding Protein and Transthyretin
• D. Gc-Globulin and a1-Antitrypsin

Answer: (A)

In inflammation, the liver shifts production toward proteins that help fight damage (positive acute-phase proteins) and away from those that are less needed during this time (negative acute-phase proteins). Negative acute-phase reactants decrease in serum levels as part of this response.

Albumin and transferrin are classic examples of negative acute-phase reactants. Albumin, the main circulating protein, drops because its synthesis is down-regulated during inflammation and its distribution changes, so its level falls. Transferrin binds iron; lowering transferrin reduces iron availability to invading microbes, which is a defense mechanism, contributing to its decrease.

Other options mix proteins that rise with inflammation (like C-reactive protein and fibrinogen, which are positive reactants) or include a protein that doesn’t consistently fit the negative category. So the combination of albumin and transferrin best fits the concept of negative acute-phase reactants.