Fig. 3

CD28 expression defines two different populations of CD4⁺NKG2D⁺ T cells in cervical cancer patients. Flow cytometry analysis of multicolor staining was performed in order to detect the expression of CD28 on selected CD3⁺CD4⁺NKG2D⁺ T cells. In (a) representative experiments show the expression of CD28 in a control sample with low percentage of CD4⁺NKG2D⁺ T cells (upper panel) and cancer sample with high percentage of CD4⁺NKG2D⁺ T cells (lower panel). In (b) we see a significant difference between patient and control samples with control CD4⁺NKG2D⁺ T cells significantly more likely to express CD28 (Mann–Whitney U-test; p = 0.008). In (c) patient and control samples were divided into groups based on percentage of CD4⁺NKG2D⁺ T cells and we see a division, with the loss of CD28 in both patients and controls that have high numbers of CD4⁺NKG2D⁺ T cells. Negative and statistically significant correlations between CD28 expression and percentages of CD4⁺NKG2D⁺ T cells are seen in both control (Spearman ρ = -0.522; p = 0.003) and patient (Spearman ρ = -0.859; p < 0.001) groups when segregated based on percentage of CD4⁺NKG2D⁺ T cells