FIGURE 5.

A1 receptor signaling is required for the ability of PMNs to kill Streptococcus pneumoniae. (a) PMNs isolated from the bone marrow of young C57BL/6 mice were treated with either the A1 receptor inhibitor 8‐cyclopentyl‐1‐3‐dipropylxanthine (3.9 nM), A2A receptor inhibitor 3,7‐dimethyl 1‐1‐propargylxanthine (11 μM), A2B receptor inhibitor MRS 1754 (1.97 nM), A3 receptor inhibitor MRS 1191 (92 nM) or PBS as vehicle control (VC) for 30 min at 37°C. (b) PMNs isolated from the bone marrow of young wild‐type (WT), A1R^−/+, and A1R^−/− mice. (a, b) PMNs were then infected with pre‐opsonized S. pneumoniae for 45 min at 37°C. Reactions were plated on blood agar plates and the percentage of bacteria killed compared to a no PMN control under the same conditions was calculated. (a, b) Data shown are pooled from three separate experiments (n = 3 mice per strain) with each condition tested in triplicate. *Significant differences versus VC reactions calculated by one‐way ANOVA followed by Dunnet's test. (c) PMNs isolated from the bone marrow of old C57BL/6 mice were treated with either the A1 receptor agonist 2‐chloro‐N6‐cyclopentyl adenosine (0.8 nM) or PBS as vehicle control (VC) for 30 min at 37°C. The reactions were infected with pre‐opsonized S. pneumoniae for 45 min at 37°C and plated on blood agar plates to determine the percentage of bacteria killed with respect to no PMN controls under the same conditions. The fold change in bacterial killing was then calculated by dividing the values of A1 receptor agonist treated reactions by vehicle treated controls for each condition. Data shown are pooled from four separate experiments (n = 4 mice per strain). *Significantly different from 1 by one‐sample t‐test