CD28 and cervical cancer: However, our current study is limited by the fact that neither the cytokine profile yielded by the different subsets of CD4+NKG2D+ T cells (characterized by the expression or lack of CD28) was evaluated, nor the effect of exogenous pro-inflammatory cytokines on these cells was assessed; thus, these experiments should be planned in the future to truly reveal the meaning of the balance between CD4+NKG2D+CD28+ T cells and CD4+NKG2D+CD28− T cells and to answer whether the CD4+NKG2D+ T cell population frequently seen in our patients promotes or discourages the growth of cervical cancer.