Related Experiment Videos
CD56 identifies monocytes and not natural killer cells in rhesus macaques
D L Carter1, T M Shieh, R L Blosser
1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Background:
CD56 is a lineage-specific marker of human natural killer (NK) cells. There are conflicts in the literature regarding the role of CD56 as a marker of NK cells in non-human primates. In the present study, we examined the role of CD56 in identifying rhesus NK cells.
Methods:
The immunophenotype of normal macaque and human NK cells was analyzed by two- and three-color flow cytometry. Flow cytometric cell sorting was subsequently used to deplete or purify NK cells; the resulting cell populations were then used in standard chromium release assays of NK lytic function.
Results:
In peripheral blood mononuclear cells of the rhesus macaque, CD56 was expressed primarily on cells with the light scatter and immunophenotypic profile of monocytes. Flow cytometric depletion of rhesus CD56(+) monocytic cells did not diminish functional activity against K562 cells, whereas depletion of CD8(+) or CD16(+) lymphocytes completely abrogated functional activity. Three-color flow cytometric analysis of CD8(+), CD16(+) lymphocytes showed that they expressed other markers (CD2, CD7, TIA-1) associated with NK cells, but notably, not CD56.
Conclusions:
These studies demonstrate that CD56 is not suitable as a marker of NK cells in the rhesus macaque.
Insights
CD56 is not a reliable marker for identifying natural killer (NK) cells in rhesus macaques. Studies show CD56 is expressed on monocytes, and its depletion does not affect NK cell function in these primates.
Area of Science:
- Immunology
- Primate immunology
Background:
- CD56 is a known marker for human natural killer (NK) cells.
- The utility of CD56 in identifying non-human primate NK cells is debated.
- This study investigates CD56's role in rhesus macaque NK cell identification.
Purpose of the Study:
- To determine if CD56 is a suitable marker for rhesus macaque NK cells.
- To clarify conflicting literature on CD56 expression in non-human primates.
Main Methods:
- Analysis of rhesus macaque and human NK cell immunophenotypes using flow cytometry.
- NK cell depletion/purification via cell sorting.
- Assessment of NK cell lytic function using chromium release assays.
Main Results:
- In rhesus macaques, CD56 was predominantly found on monocytes, not NK cells.
- Depleting CD56+ monocytes did not impair NK cell activity.
- Rhesus NK cells (CD8+, CD16+) expressed NK-associated markers but lacked CD56.
Conclusions:
- CD56 is unsuitable for identifying NK cells in rhesus macaques.
- Rhesus macaque NK cell identification requires alternative markers.