CD163 and myeloid sarcoma: CD11b (Integrin alpha‐M) belongs to the integrin‐alpha family, which is up‐regulated in chronic MS‐plaques,28 and has a broad expression spectrum including all MPs, granulocytes, and NK cells.29 CD163 is a scavenger receptor for hemoglobin‐haptoglobin complexes and is also expressed in M2 polarized macrophages in vitro.25 Four reasons may explain why we found CD11b in exp. 1 and CD163 in exp. 2: First, CD163 was only expressed in a subset of MPs and the numbers of CD163+ cells was highly variable between different tissue blocks and areas (Fig. 1J–L).