These sticky cell fragments then direct bacteria to the spleen, where they are engulfed by dendritic cells — immune cells that trigger a full-blown immune response, according to the scientists.

This process relies on the interaction between a platelet receptor called GPIb and a blood protein called C3, which sticks to bacteria.

When mice bred to lack C3 were injected with Listeria monocytogenes, platelets failed to surround the bacteria. Instead, they were destroyed by a different immune cell, the macrophage, say the scientists.

Although the macrophages cleared the bacteria, the lack of C3 prevented the formation of immunological memory — which enables the immune system to remember foreign invaders and respond to a future attack.

Ultimately, Busch says it might be possible to boost platelet response to improve vaccines.
The findings have been published in the ‘Nature Immunology’ journal.