title: Granzyme B mediated function of Parvovirus B19-specific CD4(+) T cells.
abstract: A novel conception of CD4(+) T cells with cytolytic potential (CD4(+) CTL) is emerging. These cells appear to have a part in controlling malignancies and chronic infections. Human parvovirus B19 can cause a persistent infection, yet no data exist on the presence of B19-specific CD4(+) CTLs. Such cells could have a role in the pathogenesis of some autoimmune disorders reported to be associated with B19. We explored the cytolytic potential of human parvovirus B19-specific T cells by stimulating peripheral blood mononuclear cell (PBMC) with recombinant B19-VP2 virus-like particles. The cytolytic potential was determined by enzyme immunoassay-based quantitation of granzyme B (GrB) and perforin from the tissue culture supernatants, by intracellular cytokine staining (ICS) and by detecting direct cytotoxicity. GrB and perforin responses with the B19 antigen were readily detectable in B19-seropositive individuals. T-cell depletion, HLA blocking and ICS experiments showed GrB and perforin to be secreted by CD4(+) T cells. CD4(+) T cells with strong GrB responses were found to exhibit direct cytotoxicity. As anticipated, ICS of B19-specific CD4(+) T cells showed expected co-expression of GrB, perforin and interferon gamma (IFN-γ). Unexpectedly, also a strong co-expression of GrB and interleukin 17 (IL-17) was detected. These cells expressed natural killer (NK) cell surface marker CD56, together with the CD4 surface marker. To our knowledge, this is the first report on virus-specific CD4(+) CTLs co-expressing CD56 antigen. Our results suggest a role for CD4(+) CTL in B19 immunity. Such cells could function within both immune regulation and triggering of autoimmune phenomena such as systemic lupus erythematosus (SLE) or rheumatoid arthritis.
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki , Helsinki, Finland.
authors.forename: Arun
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki , Helsinki, Finland.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Perdomo
authors.affiliation: Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki , Helsinki, Finland ; Division of Infectious Diseases, Helsinki University Central Hospital , Helsinki, Finland ; Department of Medicine, Institute of Clinical Medicine, University of Helsinki , Helsinki, Finland.
authors.forename: Anu
authors.initials: A
authors.lastname: Kantele
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki , Helsinki, Finland.
authors.forename: Lea
authors.initials: L
authors.lastname: Hedman
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki , Helsinki, Finland ; Helsinki University Central Hospital Laboratory Division, Department of Virology and Immunology , Helsinki, Finland.
authors.forename: Klaus
authors.initials: K
authors.lastname: Hedman
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki , Helsinki, Finland.
authors.forename: Rauli
authors.initials: R
authors.lastname: Franssila