CD28 and cervical carcinoma: Focusing on what appears to be a unique population of CD4+NKG2D+CD28− T cells that are overrepresented in, but not exclusive, to cervical cancer patients, cells from samples with high (>4 %) levels of CD4+NKG2D+ T cells were found to be essentially negative and very low for the presence of the markers CD107a and CD161, respectively.