Figure 7

S. suis modulates CD4⁺ T cell surface expression of CD69 and CD40L in vitro.

Bone marrow-derived dendritic cells (bmDCs) were infected with either S. suis wild-type strain P1/7 or its non-encapsulated isogenic mutant ΔcpsF (MOI: 1) for 1 h. Extracellular bacteria were killed by antibiotic treatment and cultures washed prior to addition of freshly isolated splenic CD4⁺ T cells from naive mice (T cell: DC ratio of 5: 1). Cocultures were incubated for 8 h, cells harvested and (a) CD69 or (b) CD40L expression analyzed by FACS. Cocultures incubated with medium alone served as negative controls (C−). Cocultures treated with either Concanavalin (0.1 μg/ml) or phorbol myristate acetate (15 ng/ml) + ionomycine (150 ng/ml) served as positive controls (C+) for CD69 and CD40L expression, respectively. FACS was performed using a Cell Lab Quanta^TM SC MPL MultiPlate Loader instrument. Twenty thousand gated events were acquired per sample and data analysis was performed using Cell Lab Quanta Collection/Analysis software. Quadrants were drawn based on FITC- and PE-control stains and were plotted on logarithmic scales. Representative data from 3 different experiments. Numbers in the upper quadrants indicate the % of CD4⁺CD69⁺ or CD4⁺CD40L⁺ cells.