# Strength in numbers: how multimerization drives HpHb uptake by CD163 scavenging receptor

## TL;DR

Three studies reveal how CD163 scavenges HpHb complexes by forming multimers, aiding inflammation resolution.

## Contribution

The studies show CD163's scavenging activity depends on multimer formation, using cryo-EM for near-atomic resolution.

## Key findings

- CD163 scavenges HpHb complexes through multimer formation.
- Cryo-EM reveals near-atomic structure of CD163-HpHb complex.
- Multimerization is essential for CD163's function in inflammation resolution.

## Abstract

CD163 is a macrophage scavenger receptor central to the clearance of haptoglobin-hemoglobin (HpHb) complexes and the resolution of inflammation. In a remarkable example of near-simultaneous scientific progress, three complementary studies published in Nature Communications1–3 have resolved the near-atomic resolution structure of the full extracellular domain of human CD163 complexed with HpHb, primarily utilizing cryo-electron microscopy (cryo-EM). The most significant and unified conclusion emerging from this trio of papers is that CD163’s scavenging activity is fundamentally dependent on its ability to form functional multimers.