Fig. 5. Mutation of the central cluster of basic residues in CD28_CD impairs its function in cells.

(A) T_reg cells from CD28-transduced bone marrow chimeric mice were identified by flow cytometric analysis on the basis of CD25 and intracellular FoxP3 expression after gatingon CD4⁺CD8⁻ZsGreen⁺ thymocytes (top) or CD3⁺CD4⁺ZsGreen⁺ splenocytes (bottom). Representative plots are shown for one CD28WT- and one CD28mut4-expressing sample. (B and C) The percentages of T_reg cells in the thymus (B) and spleen (C) were analyzed as shown in (A). Data are means ± SD of four independent experiments. Each dot represents an individual mouse. The CD28WT group was compared to each other group for statistically significant differences by one-way ANOVA with Dunnett’s correction for multiple comparisons.