title: Platelet microbicidal activity is an important defense factor against viridans streptococcal endocarditis.
abstract: To study the role of platelet microbicidal activity in host defense against infective endocarditis (IE) due to viridans streptococci (VS), the susceptibility to platelet releasate of blood and oral VS isolates from patients with and without IE was compared. The influence of neutralization of platelet microbicidal activity was studied in 2 experimental IE models. Resistance to platelet releasate was more prevalent among VS from blood of patients with IE than from blood of bacteremic patients without IE and among oral VS isolates. Serum from rabbits vaccinated with human platelet sonicate supernatants neutralized human and rabbit platelet-released microbicidal activity and had antibodies recognizing microbicidal proteins thrombocidin-1 and -2 and other human platelet proteins. In the 2 rabbit IE models, vaccination increased the susceptibility to experimental IE due to platelet releasate-susceptible VS. Thus, platelet-released microbicidal activity is an important host defense factor against IE due to VS.
authors.affiliation: Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands. M.J.Beets@amc.uva.nl
authors.forename: J
authors.initials: J
authors.lastname: Dankert
authors.forename: J
authors.initials: J
authors.lastname: Krijgsveld
authors.forename: J
authors.initials: J
authors.lastname: van Der Werff
authors.forename: W
authors.initials: W
authors.lastname: Joldersma
authors.forename: S A
authors.initials: SA
authors.lastname: Zaat
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents; D001422:Bacterial Adhesion; D001792:Blood Platelets / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism / Q000502:physiology*; D018925:Chemokines; D019743:Chemokines, CXC / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D004697:Endocarditis, Bacterial / Q000276:immunology / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D009500:Neutralization Tests; D015539:Platelet Activation; D011817:Rabbits; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology*; D013291:Streptococcus / Q000502:physiology*; D013917:Thrombin / Q000502:physiology; D014611:Vaccination; D001620:beta-Thromboglobulin
chemical_list: D000900:Anti-Bacterial Agents; D001798:Blood Proteins; D018925:Chemokines; D019743:Chemokines, CXC; C061615:PPBP protein, human; D001620:beta-Thromboglobulin; C077150:platelet microbicidal protein, Oryctolagus cuniculus; D013917:Thrombin