Phenotype and function of a CD56+ peripheral blood monocyte

Leukemia. 2005 Jan;19(1):69-76. doi: 10.1038/sj.leu.2403550.


G-CSF primed CD34 cells cultured for 2-3 weeks in IL-2 and stem cell factor generate CD56(high) cells with phenotypic and morphologic features of NK cells, and a novel adherent CD56(low) CD16- population expressing myeloid markers (CD33 and HLA-DR). We hypothesized that similar cells might also occur in peripheral blood. In 13/13 normal individuals, we found a circulating population of CD56(low), CD33+, FcgammaRI+, FcgammaRII+, HLA-DR+, CD11b(high), CD14+ monocytes closely resembling the cultured CD56(low)CD33+ cells. They may represent a normal counterpart of the CD56+ CD33+ hybrid myeloid/natural killer cell leukemia. Their mean frequency was 1.3+/-1% (standard deviation), range 0.16-3.5%, of total mononuclear cells. CD56(low)CD33+ cells, primed with cytomegalovirus antigen, induced autologous T-lymphocyte proliferation comparably to CD56-, CD14+ peripheral blood monocytes (PBM). Conversely, CD56(low) cells induced greater T-cell proliferation than CD56- PBM when lymphocyte responders were HLA mismatched. Unstimulated CD56(low)CD33+ cells showed a low antiproliferative effect on K562, which was increased upon LPS stimulation. The pattern of cytokine production by CD56(low)CD33+ cells and PBM largely overlapped; however, they produced detectable levels of IL-6 and IL-1beta. These results define a minor monocyte population with distinct phenotypic and functional features.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • CD56 Antigen / immunology*
  • Flow Cytometry
  • Humans
  • Interleukin-1 / metabolism
  • Interleukin-6 / metabolism
  • Monocytes / immunology*
  • Phenotype


  • CD56 Antigen
  • Interleukin-1
  • Interleukin-6