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Maurizio Provenzano

Publications and source records attributed to Maurizio Provenzano.

22 records · Page 2Linked to original sources
PubMed2003

The matrix protein pp65(341-350): a peptide that induces ex vivo stimulation and in vitro expansion of CMV-specific CD8+ T cells in subjects bearing either HLA-A*2402 or A*0101 allele.

BACKGROUND: The stimulation of PBMNCs with HLA Class I restricted synthetic peptides derived from CMV phosphorylated matrix protein 65 (pp65) evokes CMV-specific cytotoxic T lymphocyte (CTL) activity, a necessary condition for initiating adoptive immunotherapy against CMV-related diseases in immune-compromised patients. It was previously demonstrated that the CMV decamer (10-mer) peptide pp65(341-350), QYDPVAALFF, was able to induce CMV-specific CTLs in HLA-A*2402 CMV-seropositive individuals. STUDY DESIGN AND METHOD: We investigated the ability of the peptide pp65(341-350) to reactivate memory CD8+ T cells in CMV-seropositive subjects bearing either the HLA-A24 or A1 allele. CTL responses were measured by IFN-gamma mRNA expression and IFN-gamma protein production as well as cytotoxic activity. RESULTS: In this study it was found that peptide pp65(341-350) induced a specific reactivation of memory CD8+ T cells from CMV-seropositive donors expressing either HLA-A*2402 and/or HLA-A*0101. Moreover, a pp65(341-350)-specific selection and expansion using PBMNCs of CMV-seropositive donors bearing both HLA-A*2402 and HLA-A*0101 alleles produced cytotoxic CTLs to both HLA-A24 and A1 peptide-pulsed and autologous CMV-infected target cells. CONCLUSION: The results demonstrate that pp65(341-350) induced a specific CTL activity at both molecular and protein levels and that the peptide is specifically processed, presented, and recognized by subjects bearing HLA-A*2402 and/or A*0101. These findings suggest that it may be possible to use this single immune dominant peptide to induce and expand CMV-reactive CTLs for the treatment of individuals with both HLA-A24 and A1 types.

Alleles↗
PubMed2002

Functional heterogeneity of vaccine-induced CD8(+) T cells.

The functional status of circulating vaccine-induced, tumor-specific T cells has been questioned to explain their paradoxical inability to inhibit tumor growth. We enumerated with HLA-A*0201/peptide tetramers (tHLA) vaccine-elicited CD8(+) T cell precursor frequency among PBMC in 13 patients with melanoma undergoing vaccination with the HLA-A*0201-associated gp100:209-217(210 M) epitope. T cell precursor frequency increased from undetectable to 12,400 +/- 3,600 x 10(6) CD8(+) T cells after vaccination and appeared heterogeneous according to previously described functional subtypes: CD45RA(+)CD27(+) (14 +/- 2.6% of tHLA-staining T cells), naive; CD45RA(-)CD27(+) (14 +/- 3.2%), memory; CD45RA(+)CD27(-) (43 +/- 6%), effector; and CD45RA(-)CD27(-) (30 +/- 4.1%), memory/effector. The majority of tHLA(+)CD8(+) T cells displayed an effector, CD27(-) phenotype (73%). However, few expressed perforin (17%). Epitope-specific in vitro stimulation (IVS) followed by 10-day expansion in IL-2 reversed this phenotype by increasing the number of perforin(+) (84 +/- 3.6%; by paired t test, p < 0.001) and CD27(+) (from 28 to 67%; by paired t test, p = 0.01) tHLA(+) T cells. This conversion probably represented a change in the functional status of tHLA(+) T cells rather than a preferential expansion of a CD27(+) (naive and/or memory) PBMC, because it was reproduced after IVS of a T cell clone bearing a classic effector phenotype (CD45RA(+)CD27(-)). These findings suggest that circulating vaccine-elicited T cells are not as functionally active as inferred by characterization of IVS-induced CTL. In addition, CD45RA/CD27 expression may be more informative about the status of activation of circulating T cells than their status of differentiation.

CD8-Positive T-Lymphocytes↗
PubMedDate not supplied

Identification of immune dominant cytomegalovirus epitopes using quantitative real-time polymerase chain reactions to measure interferon-gamma production by peptide-stimulated peripheral blood mononuclear cells.

The identification of HLA restricted immune dominant cytotoxic T cell (CTL) epitopes limits immune therapy. Cytomegalovirus (CMV) disease remains a significant cause of morbidity after allogeneic stem cell transplantation. Adoptive immune therapy using CTLs stimulated with immune dominant CMV pp65 peptides may be effective in preventing CMV disease, but immune dominant CMV peptides have been identified for only a few HLA class I molecules. The purpose of this study was to use a novel molecular system to establish a rapid and precise method to identify new HLA-restricted CMV epitopes. Cytomegalovirus pp65 peptides expected to bind to the HLA-24 molecule were identified with a computer algorithm. Five candidate peptides were screened by direct ex vivo stimulation of peripheral blood mononuclear cells (PBMCs) from CMV-seropositive HLA-A*2402 individuals, and quantitative real time PCR (qRT-PCR) was used to evaluate CTL responses by measuring interferon-gamma (IFN-gamma) transcripts. One of the five candidate peptides, pp65341-350 (QYDPVAALFF), induced significant quantities of IFN-gamma mRNA production after 3 hours. PBMCs from CMV-seropositive HLA-A*2402 individuals sensitized in vitro with pp65341-350 also recognized CMV-infected targets. In conclusion, the measurement of IFN-gamma mRNA by qRT-PCR can be used to detect CTL responses 3 hours after peptide stimulation of a small quantity of PBMCs. This method has an advantage over other methods used to identify immune dominant epitopes in that it does not require in vitro expansion of CTLs with cytokines or virally infected targets. As a result, this method measures naturally induced immune reactions.

Antigens, Viral↗
PubMedDate not supplied

Frequency of MART-1/MelanA and gp100/PMel17-specific T cells in tumor metastases and cultured tumor-infiltrating lymphocytes.

Melanoma differentiation antigens, such as MART-1/MelanA and gp100/PMel17, frequently are observed as targets of tumor infiltrating lymphocytes (TIL) originated from HLA-A*0201-expressing patients with melanoma. Furthermore, particular clinical relevance was attributed to gp100/pMel17 based on the impression that the adoptive transfer of gp100-recognizing TIL was associated with clinical responses in a small group of patients. However, the actual frequency of specific T cells for these melanoma differentiation antigens has never been directly enumerated in ex vivo or in vitro expanded TIL cultures. Here, we enumerated melanoma differentiation antigen-specific T-cell precursor frequency in TIL using tetrameric HLA/epitope complexes, functionally characterizing their responsiveness to cognate epitope by cytokine release assay. T-cell precursor frequencies were enumerated in 11 fresh-tumor preparations and 17 TIL adoptively transferred into patients bearing HLA-A*0201. MART-1 or gp100-specific T cells could be detected respectively in 5 and 2 of the 11 fresh preparations and in 5 and 2 of the 17 adoptively transferred TIL. With one exception, melanoma differentiation antigen-specific T-cell precursor frequency in fresh material and TIL ranged between 5,000 to 21,000/10(6) CD8+ T cells. T-cell precursor frequency was not significantly higher in TIL whose administration was associated with clinical response. These data provide direct enumeration of MART-1/MelanA and gp100/pMel17 reactivity ex vivo and in vitro in the context of HLA-A*0201.

Antigens, Neoplasm↗