The invention relates to a method for establishing functional cytokine memory in a cell and/or cell population via demethylation of one or more regulatory nucleic acid sequences associated with the cytokine-encoding nucleic acid sequence. The invention further relates to a method for identifying functional cytokine memory in a cell and/or cell population via analysis of DNA methylation of one or more regulatory DNA sequences associated with a nucleic acid sequence encoding the cytokine. The invention further relates to the memory T cells generated by the method of the present invention for use in cell therapy, preferably in the treatment of cancer, autoimmune diseases or infectious diseases. Another aspect of the invention relates to a method of disease diagnosis and/or monitoring disease progression, preferably before, during and/or after medical treatment, comprising analysis of memory T cells for identifying functional cytokine memory whereby the proportion of memory T cells exhibiting functional cytokine memory for one or more particular cytokines provides a quantitative or semi-quantitative assessment of disease presence and/or progression.
