However, a preferential retention of effector memory over central memory lymphocytes has been observed in most donors.
Based on CCR7, CD45RO, CD28 and CD95 surface expression, it is possible to discriminate six differentiation stages of human T cells: naïve (Tn), stem cell memory (Tscm), central memory (Tcm), transitional memory (Ttm), effector memory (Tem) and terminal effector (Tte 33.
TCD8+ cells may be divided into subsets with different phenotypes and functions: naive, central memory, effector memory and effector.
Teixeiro, E. et al. Different T cell receptor signals determine CD8+ memory versus effector development.
Both TSCM and TMNP cells, which express naive T cell markers (CD45RA+CD45RO−CCR7+CD62L+), respond rapidly to antigens, express multiple effector molecules and produce memory and effector cells.
Speiser, D. E. et al. Memory and effector CD8 T-cell responses after nano-particle vaccination of melanoma patients.
The phenotypic analysis of human CD8+ T cells showed that CD27highCD28+CD45RA+CCR7+, CD27+CD28+CD45RA−CCR7+, CD27+CD28+CD45RA−CCR7−, CD27lowCD28−CD45RA+/−CCR7−, and CD27−CD28−CD45RA+/−CCR7− have characteristics of naive, central memory, early effector memory, late effector memory, and effector CD8+ T cells, respectively [22], [23].
Proportions of CD4 or CD8 T cells with naïve, central memory, effector memory, or effector phenotype did not change significantly in either group (data not shown).
We further characterized the differentiation stages of the responding T cells as falling into central memory (TCM), effector memory (TEM), or terminal effector (TEF) stages.
Most memory and effector lymphocytes also access and recirculate through extra-lymphoid immune effector sites.
