Fig. 1: CD28 stimulation drives proliferation of memory T cells.

A, B Purified CD4⁺CD25⁻ memory and naive T cells were CTV stained and stimulated for 5 days in the presence of CD86 transduced DG75 B cells, TSST-1 superantigen and abatacept at the indicated concentrations. The proliferation of Vβ2+ T cells was determined via flow cytometry and the number of cells within the ‘Dividing Vβ2+’ gate calculated using Accucheck counting beads and FLOWJO proliferation software. B Boxplots represent the number of cells within the ‘Dividing Vβ2+’ gate relative to controls (no abatacept) for each dose of TSST-1. C Purified CTV stained CD4⁺CD25⁻ memory and naive were stimulated with anti-CD28 or anti-CD3 in the presence of CHO-FcR transfectants. The proliferation of memory and naive T cells was measured by flow cytometry five days following stimulation. The proliferation index and precursor frequency were determined using the proliferation calculator of FLOWJO software. D Purified CTV stained CD4⁺CD25⁻ memory and naive were stimulated in the presence of CD86 transduced DG75 cells at a T:DG ratio of 1:1 and indicated concentrations of soluble anti-CD3 for 5 days. Proliferation was determined by flow cytometry. B–D Significance was calculated using two-way ANOVA and group means were compared using Tukey’s honest significant difference test.