Anti-bacterial activity mediated by human platelets.

Platelet-mediated antibacterial activity against gram-negative microorganisms has been investigated. Data show that human washed platelets possess the ability to partially inhibit growth of Salmonella typhi Ty-2 (a smooth strain) but not of two rough strains of Salmonella minnesota (R345-Rb and R595-Re). On the other hand, no antibacterial activity was noted in the presence of the gram-positive Staphylococcus aureus. This activity is dependent on the length of incubation of platelets with bacteria and apparently is not mediated by platelet soluble factors. Finally, lysis of platelets with Triton X-100 following their incubation with bacteria gives rise to the same degree of antibacterial activity observed in the untreated samples. This implies that the described platelet function does not rely on the possible trapping of bacteria in platelet aggregates.