Identification of HLA-A33-restricted CMV pp65 epitopes as common targets for CD8(+) CMV-specific cytotoxic T lymphocytes.
OBJECTIVE
To identify an immunodominant HLA-A33-restricted epitope within the CMV matrix phosphoprotein 65 (pp65) that could be used to elicit CMV-specific CTLs.


METHODS
A computer algorithm was used to identify pp65 peptides that were expected to bind to HLA-A33. The peptides were screened for their ability to reactivate memory T lymphocytes from CMV-seropositive HLA-A33 donors by using quantitative real-time RT-PCR. The most promising peptides were then tested for their ability to expand a CD8(+) population of HLA-A33 CTLs that produced interferon-gamma (IFN-gamma) and were cytotoxic to either peptide-loaded or CMV-infected target cells.


RESULTS
Sixteen out of 250 peptides were selected using a computer algorithm and peptide stimulation by 8 out of the 16 induced a significant quantity of IFN-gamma mRNA transcript from CMV-seropositive HLA-A33 peripheral blood mononuclear cells. All the eight peptides induced consistent T-cell reactivation. One specifically, the peptide pp65(91-100) (SVNVHNPTGR), proved to be more active. T cells in vitro sensitized for 2 or 3 weeks with pp65(91-100) were cytotoxic to both HLA-A33 peptide-loaded and CMV-infected target cells.


CONCLUSIONS
CMV pp65(91-100) is a new HLA-A33-restricted peptide that broadens the list of antigenic determinants that can be used for CMV adoptive immunotherapy.
Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea.
Jong-Baeck
JB
Lim
Maurizio
M
Provenzano
Oh Hun
OH
Kwon
Maria
M
Bettinotti
Lorraine
L
Caruccio
Dirk
D
Nagorsen
David
D
Stroncek
D000595:Amino Acid Sequence; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D005434:Flow Cytometry; D015234:HLA-A Antigens / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014763:Viral Matrix Proteins / Q000276:immunology*
D000939:Epitopes; D015234:HLA-A Antigens; C082945:HLA-A*33 antigen; D010750:Phosphoproteins; D012333:RNA, Messenger; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D007371:Interferon-gamma