CD33 and rheumatoid arthritis: With regard to phenotype, we have found that the majority of MDSC-like RA SF cells belongs the granulocytic CD11b+CD33+HLA-DRlo/-CD14−CD15+ subset with neutrophil morphology; only a very small population of the CD11b+CD33+HLA-DRlo/-CD14+CD15− monocytic subset could be identified in the patients’ SF samples.