Different methods to detect viral and tumor Ag-specific CD4+ T cells in healthy carriers or infected individuals and neoplastic patients are being used (i.e., ELISPOT assay, intracellular cytokine detection by flow cytometry, proliferation and cytokine release assays, tetramer staining and limiting dilution assay) with different pros and cons [7], [8], [9], [10], [11], [12], [13], [14]. The gene discussed is CD4; the disease is neoplasm.