FIGURE 4.

Engagement of Siglec-5 with β-protein and its effect on T cell effector functions. Naïve CD4 or CD8 T cells were cultured with plate bound anti-CD3 and anti-CD28 stimulation in the presence of IL-2 for 3 days. Cells were than harvested and re-stimulated with plate bound anti-CD3, anti-CD28 and B6N::sfGFP or sfGFP. Supernatants and cells from the 3 days cultures were collected and used for (a) and (b) cytokine bead array analysis and (c) measurement of Granzyme B production. Statistical analysis: Ratio paired two-tailed t test; *p < 0·05, **p < 0·01. (d) Day 3 stimulated CD4 T cells were re-stimulated with plate bound anti-CD3, anti-CD28 and B6N::sfGFP or sfGFP pre-incubated with hIgG1 Fc or Siglec-5 Fc at equimolar ratios. At day 3 post-re-stimulation, cytokine production and Granzyme B expression were measured. For each condition, treatments were normalized to unstimulated values first. Fold change was than calculated as the ratio of cells stimulated in the presence of B6N::sfGFP vs sfGFP. Statistical analysis: one-way ANOVA, Tukey’s multiple comparisons test, **p < 0·01. Each dot represents an individual donor