[1] Herttoniemi Hosp, Helsinki 00800, Finland
[2] Univ Helsinki, Haartman Inst, Dept Bacteriol & Immunol, FIN-00014 Helsinki, Finland
[3] Repolar Oy, Espoo 02101, Finland
[4] Univ Helsinki, Cent Hosp Lab, HUSLAB, FIN-00014 Helsinki, Finland
[5] Uppsala Univ, Dept Med Sci, SE-75185 Uppsala, Sweden