title: Plasma contributes to the antimicrobial activity of whole blood against Mycobacterium tuberculosis.
abstract: The whole blood model for infection has proven useful to analyze the immunological response to Mycobacterium tuberculosis, because it exerts a significant antimicrobial activity. Although this activity has been generally assumed to be cellular, we have found that the leukocyte fraction of blood from healthy volunteers did not kill the bacilli. We have discovered that plasma was responsible for a large proportion, but not all, of the antimicrobial activity. Furthermore, infected monocytes controlled the mycobacterial multiplication when cultivated in the presence of plasma. Intriguingly, serum from the same donors did not share this activity, although it was able to eliminate the non-pathogenic Mycobacterium gordonae To identify the remaining components that participate in the antimycobacterial activity we fractionated blood in leukocytes, plasma, erythrocytes and platelets, and analyzed the bactericidal power of each fraction and their combinations using a factorial design. We found that erythrocytes, but not platelets, participated and showed by flow cytometry that mycobacteria physically associated with erythrocytes. We propose that in exposed healthy individuals that show 'early clearance' of the mycobacteria, the innate response is predominantly humoral, probably through the effect of antimicrobial peptides and proteins.
authors.affiliation: Servicio de Microbiología, Hospital Comarcal del Bierzo, León, Spain.
authors.forename: Ramiro
authors.initials: R
authors.lastname: López-Medrano
authors.affiliation: Servicio de Medicina Interna, Complejo Asistencial Universitario de León, (CAULE), León, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Guerra-Laso
authors.affiliation: Unidad de Investigación, Complejo Asistencial Universitario de León (CAULE), León, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: López-Fidalgo
authors.affiliation: Servicio de Anatomía Patológica, Complejo Asistencial Universitario de León (CAULE), León, Spain Institute of Biomedicine (IBIOMED), Universidad de León, León, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Diez-Tascón
authors.affiliation: Servicio de Neumología, Complejo Asistencial Universitario de León (CAULE), León, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: García-García
authors.affiliation: Servicio de Análisis Clínicos, Complejo Asistencial Universitario de León (CAULE), León, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Blanco-Conde
authors.affiliation: Unidad de Investigación, Complejo Asistencial Universitario de León (CAULE), León, Spain Institute of Biomedicine (IBIOMED), Universidad de León, León, Spain Fundación Instituto de Estudios de Ciencias de la Salud de Castilla y León (IECSCYL), León, Spain omrivero@iecscyl.com.
authors.forename: Octavio Miguel
authors.initials: OM
authors.lastname: Rivero-Lezcano
mesh_terms: D000900:Anti-Bacterial Agents / Q000276:immunology*; D001770:Blood Bactericidal Activity; D048708:Cell Growth Processes; D002478:Cells, Cultured; D004912:Erythrocytes / Q000276:immunology* / Q000382:microbiology; D064368:Healthy Volunteers; D006801:Humans; D056724:Immunity, Humoral; D009000:Monocytes / Q000276:immunology* / Q000382:microbiology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D009170:Nontuberculous Mycobacteria / Q000276:immunology*; D010949:Plasma / Q000276:immunology*; D013045:Species Specificity; D014397:Tuberculosis, Pulmonary / Q000276:immunology*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Legionella pneumophila; erythrocyte; monocytes; plasma; serum; susceptibility