Beyond hemostasis, the immunomodulatory nature of platelets

In addition to playing a key role in hemostasis, platelets are involved in immunomodulatory processes against pathogenic infection. Platelets secrete substances and express membrane proteins that form part of the immune defense environment to effectively remove pathogens. Direct or indirect contact of pathogens with platelets can activate platelets, which subsequently elicit a range of immune responses in vivo, leading to pathogen clearance, evasion, or tissue damage. This review summarizes the immune functions of platelets beyond hemostasis, their interactions with other immune components such as the complement system, neutrophils, and monocytes, and specifically highlights the immune effects exerted by platelets against several microbial infections.