Natural killer cells (NK-cells):
Family of innate lymphoid cells
Do not express antigen receptors: lineage markers CD3 and CD19 are negative
Express:
- CD2, CD7, CD56, NCAM
- Activating receptors: CD16, CD335, CD336, CD337
- Inhibitory receptors: CD94/NKG2A, KIR/CD158
- Variable CD11b, CD11c, CD38, CD45RA, CD45RO, HLA-DR, CD57 depending on activation status
- Non-activated: CD2dim/-, CD7bright, CD38+, CD45RA+, CD45RO-, HLA-DR-, variable CD57, CD11c
- Small CD2- CD5+ subsets can be seen in blood and spleen
2 subsets based on expression of CD16 and CD56
- CD56dim CD16bright, KIR+, CD94heterogeneous, variable CD57, perforin, granzymeB: predominant in PB (90%), cytotoxic activity
- CD56bright CD16-/dim, KIR-, CD94bright: mostly in lymphoid tissues (10% of circulating), influence immune response via release of cytokines
Normal NK-cell immunophenotype (bone marrow aspirate)
Normal NK-cell immunophenotype (peripheral blood)
Normal/reactive variations
- Acute viral infections: higher CD38 and HLA-DR, decreased CD45RA co-expressed with CD45RO, homogeneously CD11c+, mostly CD57-
- Chronic viral infections or neoplasia: late activating NK-cells
- Positive CD57
- Decreased CD7, CD38 and CD11b
- Negative CD11c, HLA-DR, CD45RO
Next page: Example of CMV reactivation
Previous page: T-cell Development and Normal Subsets