Nontoxic concentrations of dipyridamole reduce TNF-α levels and phagocytic capacity of activated microglia.
(A) An ATP luminescence assay demonstrates that dipyridamole does not adversely affect viability to at least 20 μM. (B) TNF-α increases due to the addition of lipopolysaccharide (LPS) to microglia are attenuated by dipyridamole in a concentration-dependent fashion. **P < 0.01, ***P < 0.001 compared to LPS group. All values are means ± SEM (n = 4 wells per column) and were reproduced in three separate experiments. (C) The phagocytic capacity of microglia (Iba-1 label, red) is demonstrated by their ingestion of microfluorospheres (green) that were added to the culture medium. Note that this is an example of beads captured in a cell and that the quantitation in panel (D) depicts the results captured from all the cells in each well. Original magnification, ×200. (D) The total increase in bead intensity per cell due to LPS activation is attenuated by 10 μM dipyridamole (DP). Mean ± SEM of four wells per column. ***P < 0.001.