Phenotypic classification of human CD8⁺ T cells reflecting their function: inverse correlation between quantitative expression of CD27 and cytotoxic effector function

Abstract

Phenotypic classification of human CD8 + T cells using three cell surface markers, CD27, CD28 and CD45RA, was recently suggested to be useful for identification of naive, memory and effector CD8 + T cells. However, it still remains unclear whether such classification precisely reflects functional classification of CD8 + T cells. To clarify this, we characterized each CD27CD28CD45RA subset of total and human cytomegalovirus (HCMV)-specific CD8 + T cells by analyzing the expression of perforin and two chemokine receptors, CCR5 and CCR7, as well as their function. An inverse correlation between perforin and CD27 expression was found in all four CD28CD45RA subsets. Therefore, to achieve a phenotypic classification of CD8 + T cells that more precisely reflects their function, the CD27 + subset was divided into CD27 low and CD27 high subsets based on the expression level of CD27. Functional and flow cytometric analyses of CD27CD28CD45RA subsets showed that this phenotypic classification reflects functional classification of CD8 + T cells. HCMV-specific CD8 + T cells from healthy HCMV-seropositive individuals were predominantly found in effector and memory/effector subsets, indicating that HCMV-specific effector CD8 + T cells are actively induced by HCMV replication in healthy HCMV carriers. Phenotypic analyses of CD8 + T cells using this classification will enable the characterization of antigen-specific CD8 + T cells.

Down‐regulation of CXCR4 expression on human CD8+ T cells during peripheral differentiation

“…The correlation between the expression of CXCR4 and CCR7 or CCR5 on CD8 + T cells CCR7 is expressed on naive CD8 + T cells and a portion of memory CD8 + T cells [7,15,21,22], while CCR5 is predominantly expressed on memory CD8 + T cells and a some effector CD8 + T cells [15,23,27]. These observations suggest that the expression of CXCR4 is positively correlated with that of CCR7, but is not correlated with that of CCR5.…”

“…It is known that perforin is expressed in effector and memory/effector CD8 + T cells [6,14,15]. Since CXCR4 + cells were predominantly detected in CD8 + T cells with naive and memory phenotypes, the assumption is that the expression of CXCR4 is negatively correlated with that of perforin.…”

“…Phenotypic classification of memory and effector CD8 + T cells has proven to be very useful in mouse and human immunological studies. In humans, the particular expression patterns of the costimulatory molecules CD27 and CD28 as well as CD45RA or CD45RO are associated with naive, memory and effector function of CD8 + T cells [7,[9][10][11][12][13][14][15]. Indeed, effector and memory/effector CD8 + T cells that were classified by the phenotypes of CD27 -CD28 -CD45RA +/-and CD27 low CD28 -CD45RA +/-, respectively, possess cytotoxic activity and the ability to produce cytokines [6,7,14,15].…”

“…Chemokine receptors are also useful as surface markers to discriminate naive, memory and effector subsets in human CD8 + T cells. CCR7 is expressed on naive and memory CD8 + T cells as a homing receptor to secondary lymphoid tissues [7,15,21,22]. CCR5 is expressed on memory and memory/effector CD8 + T cells and decreases during differentiation from memory to effector CD8 + T cells; CD27 + CD28 + CD45RA -?…”

“…CD27 + CD28 -CD45RA -? CD27 -CD28 -CD45RA - [7,15,23]. A recent study demonstrated that CXCR1 is expressed on effector and effector/memory CD8 + T cells with phenotypes of CD27 -CD28 -CD45RA +/-and CD27 low CD28 -CD45RA +/-, respectively, and that the expression of CXCR1 correlates with that of perforin [24].…”