Cytotoxic capacity of hepatitis C virus (HCV)--specific lymphocytes after in vitro immunization with HCV-derived lipopeptides.
BACKGROUND
Hepatitis C virus (HCV)-derived lipopeptides can induce epitope-specific immune responses in lymphocytes from HCV-naive individuals. We analyzed whether such T cells generated by in vitro immunization with HCV core-derived lipopeptides exert HCV-specific cytolytic activity.


METHODS
Using a sensitive flow cytometric cytotoxicity assay we characterized HCV-specific cytotoxicity in T cells generated in vitro with HCV core-derived 25-mer lipopeptides. In addition, we studied expressions of Fas ligand and perforin and interferon-gamma (IFN-gamma) secretion in HLA-A2-HCV(core_35-44) tetramer-positive T cells generated with lipopeptide amino acid 20-44 (LP20-44).


RESULTS
CD8+ T cells induced in vitro with HCV core-derived lipopeptides only infrequently exerted HCV-specific cytotoxicity, irrespective of whether antigen-coated T2 cells or autologous B lymphoblasts were used as targets. Detailed analysis of HLA-A2-HCV(core_35-44) tetramer-positive T cells generated with LP20-44 revealed that in vitro immunization resulted in T cells that secreted IFN-gamma after antigen-specific restimulation and that upregulated expression of Fas ligand but not of perforin.


CONCLUSIONS
Our data confirm at the functional level that HCV lipopeptides induce antigen-specific T lymphocytes that produce IFN-gamma but exert significant cytotoxicity in only a minority of experiments, probably because expression of cytolytic effector molecules is not enhanced in their granules.
Langhans
Bettina
B
Department of Internal Medicine I, University of Bonn, Germany.
Schweitzer
Susann
S
Braunschweiger
Ingrid
I
Schulz
Monika
M
Sauerbruch
Tilman
T
Spengler
Ulrich
U
D000328:Adult; D000483:Alleles; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D003601:Cytotoxicity Tests, Immunologic; D053222:Fas Ligand Protein; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D016174:Hepacivirus / Q000276:immunology*; D006801:Humans; D007114:Immunization; D007371:Interferon-gamma / Q000378:metabolism; D008074:Lipoproteins / Q000096:biosynthesis / Q000276:immunology*; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D010641:Phenotype; D012680:Sensitivity and Specificity; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000821:virology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000821:virology; D014758:Viral Core Proteins / Q000096:biosynthesis / Q000276:immunology*; D014761:Viral Hepatitis Vaccines / Q000276:immunology*
C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008074:Lipoproteins; D008562:Membrane Glycoproteins; D014758:Viral Core Proteins; D014761:Viral Hepatitis Vaccines; D007371:Interferon-gamma