The present invention relates to the field of tumor immunology. It provides a method for identifying mutation-related human CD8+ T cells, in particular, tumor-specific T cells of a human subject, comprising analyzing CD8+ T cells of the subject by analysing the expression of at least one marker selected from a first group consisting of CD82, CD194, CD244, CD28, CD62L and CD55, and preferably, a marker selected from a second group comprising CD11a or CD18 or CD43. A preferred marker for mutation-related CD8+ T cells is CD82, which may be analysed in combination, e.g., with CD11a. Without the need to identify any epitope to which T cells reacts, this method can advantageously be used to isolate the entire individual pool of mutation-related T cells, and, optionally, to identify the sequence of a mutation-related TCR, which allows for generation of transgenic T cells expressing the TCR. Compositions substantially comprising tumor-specific CD82.sup.hiCD8+ T cells and/or CD194.sup.hi, CD244.sup., CD28.sup.+, CD62L.sup.+ and/or CD55.sup.+ CD82.sup.hiCD8+ T cells can be used for treatment of a cancer patient, e.g., by adoptive T cell transfer. The method of the invention can also be used for diagnostic purposes to identify human mutation-related T cells or diagnosing a tumor disease or for testing responses of a cancer patient to an immune stimulatory therapy, preferably, a therapy with a checkpoint inhibitor.