CD163: Marker for intermediate and late stage Inflammatory Macrophages

Introduction

CD163 is a highly expressed macrophage membrane protein belonging to the scavenger receptor cysteine rich (SRCR) domain family. The CD163 expression is induced by interleukin-6, interleukin-10 and glucocorticoids. Its function has remained unknown until recently when CD163 was identified as the endocytic receptor binding hemoglobin (Hb) in complex with the plasma protein haptoglobin (Hp). This specific receptor-ligand interaction leading to removal from plasma of the Hp-Hb complex-but not free Hp or Hb now explains the depletion of circulating Hp in individuals with increased intravascular hemolysis. The novel functional linkage of CD163 and Hp, which both are induced during inflammation, also reveal some interesting perspectives relating to the suggested anti-inflammatory properties of the receptor and the Hp phenotypes. Cross-linking of CD163 on glucocorticoid-stimulated macrophages results in the secretion of several proinflammatory cytokines, but the precise mechanism of CD163 mediated signal transduction is not understood. Recent studies showed that the regulatory beta-subunit of casein kinase II (CKII) specifically binds to the cytoplasmic domain of CD163. Furthermore, it was demonstrated that the cytoplasmic domains of CD163 variants are phosphorylated by PKC-alpha in vitro. Inhibition studies using specific kinase inhibitors revealed that both CKII and PKC are involved in the CD163 signaling mechanism resulting in the secretion of proinflammatory cytokines.

Antibody Tools for Detection of human CD163

Ki-M8 and RM3/1 were the first clones specific to human CD163. All the initial research on that protein was performed using these clones. Meanwhile Acris Antibodies offers a panel of monoclonal antibodies to CD163 for use in flow cytometry or other immunological applications like Western blot or immunohistochemistry.

Fig.1: Paraffin sections of human tonsils using 5C6-FAT

Fig.2: Frozen sections of human placenta using RM3/1

Available antibody panel to CD163

CD163 antibody

References

Graverson, J. H. et al, Int J Biochem Cell Biol. 2002 Apr; 34(4):309-14.

Ritter, M. et al, Eur J Immunol. 2001 Apr; 31(4):999-1009

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