Phenotypic and transcriptional profile correlates with functional plasticity of antigen‐specific CD4 + T cells

The role of CD4 + T cells in the control of infectious pathogens is highly complex with a myriad of functions but how these T cells acquire differential functional potentiality remains poorly defined. Here we show that human cytomegalovirus (CMV)‐specific CD4 + T cells directed towards different viral antigens expressed predominantly TNF‐α alone or TNF‐α and IFN‐γ. TNF‐α + and IFN‐γ + CD4 + T cells expressed significantly higher levels of T‐box transcription factors T‐bet with graded loss of Eomesodermin (Eomes) expression (T‐bet Hi Eomes Hi/Lo ) when compared with TNF‐α + CD4 + T cells expressing lower levels of both T‐bet and Eomes (T‐bet − Eomes − ). Furthermore, TNF‐α + and IFN‐γ + CD4 + T cells expressed significantly higher levels of perforin and interleukin (IL)‐2 and displayed a terminally differentiated phenotype (CCR7 − CD27 − CD45RA − CD57 + CD62L − ). In contrast, TNF‐α + alone CMV‐specific CD4 + T cells were predominantly early‐memory phenotype with a proportion of these cells displaying T memory stem‐cell phenotype (CD95 + CD45RA + CCR7 + CD27 + ). In vitro stimulation of CMV‐specific CD4 + T cells with viral antigen in the presence of IL‐12 was sufficient to dramatically change the transcriptional and functional profile of TNF‐α + CD4 + T cells, whereas TNF‐α + and IFN‐γ + CD4 + T cells remained unaltered. These findings illustrate an intrinsic link between cytokine expression, transcriptional regulation and cellular differentiation, and their impact on functional plasticity of virus‐specific CD4 + T cells.