CD4 and non-small cell lung carcinoma: Several studies have shown that CD4+ T cells can recognize tumor antigens presented on the surface of tumor cells and directly activate anti-tumor immunity associated with MHC class II molecules.[9] Srivastava et al demonstrated that activated tumor-specific CD4+ T cells may be useful for the treatment of NSCLC.[10] In addition, CD4+ T cells were found to correspond to sex and age in mice.[11] Our findings revealed that there was a higher proportion of memory-activated CD4+ T cells in younger women.