Pathogen-Specific Circulating Plasmablasts in Patients with PneumoniaReportar como inadecuado

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Lower respiratory tract infections LRTI are the leading cause of death world-wide, with Streptococcus pneumoniae Pnc as the most prevalent pathogen. Local immune mechanisms appear central to protection against the disease, yet they are poorly characterized. Infections at other, non-respiratory mucosal sites are associated with a transient circulation of mucosa-originating lymphocytes from the mucosal site to blood and back to the mucosa. The present study explored whether pathogen-specific plasmablasts appear in the circulation also in patients with infection of the lower respiratory tract. 16 patients with bacteremic Pnc pneumonia and 14 healthy volunteers were explored for circulating plasmablasts secreting antibodies against their own pathogenic Pnc strain isolated in blood cultures patients or against several pathogenic strains from pneumonia patients 14 controls or a mixture of nine different purified pneumococcal polysaccharides 8 controls. Both patients and volunteers were studied for all plasmablasts. The cells were identified with ELISPOT as Pnc-specific antibody-secreting cells ASC and as all immunoglobulin-secreting cells ISC. High numbers of circulating Pnc-specific ASC were found in the acute phase of the disease in all patients with pneumonia median 97 ASC-106 PBMC, but in none of the controls. IgG isotype predominated in 9-16 patients. The numbers of ISC were significantly higher in the patients than in the healthy controls, yet Pnc-specific ASC only accounted for 0.7% of all the patients- ISC.The present study is the first to show that antigen-specific plasmablasts appear in the circulation in pneumonia, suggesting that pulmonary lypmhocytes recirculate in humans. Assessing these cells provides a novel tool for studying immune response to antigens encountered at the LRT.

Autor: Nina V. Palkola , Sari H. Pakkanen , Jussi M. Kantele, Niina Rossi, Ritvaleena Puohiniemi, Anu Kantele



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