CD4 and neoplasm: The discrepancies in the results may be due to the activation status as well as the heterogeneity in the expression profiles of these cells in differential states of anti-tumor immune responses, since similar to CD4+ helper lymphocytes, CTLs are also classified into different subsets based on their transcription factors, cytokine profiles, and effector functions, which could dramatically affect the outcome of the host–tumor interaction [157].