Dr. W. Martin Kast graduated summa cum laude in Medical Biology in 1983 and got his Ph.D. summa cum laude in Medicine in 1987, both from the University of Amsterdam, The Netherlands. He held faculty positions at the Netherlands Cancer Institute, the University of Leiden, the University of Pittsburgh and Loyola University Chicago. He currently holds the Walter A. Richter Chair in Cancer Research and is a Professor of Molecular Microbiology Phone: 3234423870 Address: 1450 Biggy Street, Los Angeles, CA 90033, USA
High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) th... more High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) that induce and maintain the malignant phenotype. The viral origin of these proteins makes them attractive targets for development of a therapeutic vaccine. Camelid-derived single-domain antibody fragments (nanobodies or VHHs) that recognize cell surface proteins on antigen-presenting cells (APCs) can serve as targeted delivery vehicles for antigens attached to them. Such VHHs were shown to induce CD4+ and CD8+ T-cell responses against model antigens conjugated to them via sortase, but antitumor responses had not yet been investigated. Here, we tested the ability of an anti-CD11b VHH (VHHCD11b) to target APCs and serve as the basis for a therapeutic vaccine to induce CD8+ T cell responses against HPV+ tumors. Mice immunized with VHHCD11b conjugated to an H-2Db-restricted immunodominant E7 epitope (E749-57) had more E7-specific CD8+ T cells compared to those immunized with E749-57 peptide a...
High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) th... more High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) that induce and maintain the malignant phenotype. The viral origin of these proteins makes them attractive targets for development of a therapeutic vaccine. Camelid-derived single-domain antibody fragments (nanobodies or VHHs) that recognize cell surface proteins on antigen-presenting cells (APCs) can serve as targeted delivery vehicles for antigens attached to them. Such VHHs were shown to induce CD4+ and CD8+ T-cell responses against model antigens conjugated to them via sortase, but antitumor responses had not yet been investigated. Here, we tested the ability of an anti-CD11b VHH (VHHCD11b) to target APCs and serve as the basis for a therapeutic vaccine to induce CD8+ T cell responses against HPV+ tumors. Mice immunized with VHHCD11b conjugated to an H-2Db-restricted immunodominant E7 epitope (E749-57) had more E7-specific CD8+ T cells compared to those immunized with E749-57 peptide a...
Human papillomavirus (HPV)-mediated suppression of Langerhans cell (LC) function can lead to pers... more Human papillomavirus (HPV)-mediated suppression of Langerhans cell (LC) function can lead to persistent infection and development of cervical intraepithelial neoplasia (CIN). Women with HPV-induced high-grade CIN2/3 have not mounted an effective immune response against HPV, yet it is unknown if LC-mediated T cell activation from such women is functionally impaired against HPV. We investigated the functional activation of in vitro generated LC and their ability to induce HPV16-specific T cells from CIN2/3 patients after exposure to HPV16 followed by treatment with stabilized Poly-I:C (s-Poly-I:C). LC from patients exposed to HPV16 demonstrated a lack of costimulatory molecule expression, inflammatory cytokine secretion, and chemokine-directed migration. Conversely, s-Poly-I:C caused significant phenotypic and functional activation of HPV16-exposed LC, which resulted in de novo generation of HPV16-specific CD8(+) T cells. Our results highlight that LC of women with a history of persis...
Cytokines and Growth Factors in Blood Transfusion, 1997
Effector T cells recognize immunogenic peptides that are presented on the cell membrane in the co... more Effector T cells recognize immunogenic peptides that are presented on the cell membrane in the context of major histocompatibility complex (MHC) molecules. The vast majority of T cells consists of either CD8+ cytotoxic T lymphocytes (CTL) or CD4+ T helper cells. By and large, MHC class I molecules present antigenic peptides to CTL, whereas T helper cells recognize antigenic peptides in the context of MHC class II molecules. These proteins are mainly found on the cells of the immune system with a specialized antigen presenting function. In general, CD4+ lymphocytes secrete cytokines upon triggering that controles the activation of B cells, macrophages and CD8+ cells. MHC class I molecules are expressed on the cell surface of virtually all nucleated cells and present peptides derived from endogenously synthesized proteins to CTL. This enables the CTL to screen almost all cells of the body for antigenic peptides that may be presented as a consequence of viral infection or malignant transformation. Therefore, the CD8+ CTL represent a major effector subset of tumour-specific T cells responsible for rejection of tumours.
The aim of this study was to classify the diversity of anal HPV and non-HPV sexually transmitted ... more The aim of this study was to classify the diversity of anal HPV and non-HPV sexually transmitted infections (STIs) and compare the concordance between anal and genital infections in HIV-infected and uninfected women living in the Tapajós region, Amazon, Brazil. A cross-sectional study was performed with 112 HIV-uninfected and 41 HIV-infected nonindigenous women. Anal and cervical scrapings were collected and analyzed for HPV, Chlamydia trachomatis (CT), Neisseria gonorrheae (NG), Trichomonas vaginalis (TV), Mycoplasma genitalium (MG), and Human alphaherpesvirus 2 (HSV-2). The Kappa test evaluated the concordance between anal and genital infections. The overall prevalence of anal HPV infection was 31.3% in HIV-uninfected and 97.6% in HIV-infected women. The most frequent anal high-risk HPV (hrHPV) types were HPV18 and HPV16 in HIV-uninfected women and HPV51, HPV59, HPV31, and HPV58 in HIV-infected women. Anal HPV75 Betapapillomavirus was also identified. Anal non-HPV STIs were identi...
Human papillomavirus (HPV) entry into epithelial cells is independent of canonical endocytic path... more Human papillomavirus (HPV) entry into epithelial cells is independent of canonical endocytic pathways. Upon interaction with host cells, HPV establishes infection by traversing through an endocytic pathway that is clathrin- and caveolin-independent, but dependent on the annexin A2/S100A10 heterotetramer (A2t). We examined the contribution of monomeric annexin A2 (AnxA2) vs. A2t in HPV infection and endocytosis, and further characterized the role of these molecules in protein trafficking. We specifically show that cell surface A2t is not required for HPV attachment, and in the absence of A2t virion internalization remains clathrin-independent. Without A2t, viral progression from early endosomes to multivesicular endosomes is significantly inhibited, capsid uncoating is dramatically reduced, and lysosomal degradation of HPV is accelerated. Furthermore, we present evidence that AnxA2 forms a complex with CD63, a known mediator of HPV trafficking. Overall, the observed reduction in infe...
Multiple solid cancers contain tertiary lymphoid organs (TLO). However, it is unclear whether the... more Multiple solid cancers contain tertiary lymphoid organs (TLO). However, it is unclear whether they promote tumor rejection, facilitate tumor evasion, or simply whether they are a byproduct of chronic inflammation. We hypothesize that although chronic inflammation induces TLO formation, the tumor milieu can modulate TLO organization and functions in prostate cancer. Therefore, our study seeks to elucidate the cellular and molecular signatures in unique prostatectomy specimens from evanescent carcinoma patients to identify markers of cancer regression, which could be harnessed to modulate local immunosuppression or potentially enhance TLO function. We used multicolor immunofluorescence to stain prostate tissues, collected at different stages of cancer progression (prostatic intraepithelial neoplasia, intermediate and advanced cancer) or from patients with evanescent prostate carcinoma. Tissues were stained with antibodies specific for pro-inflammatory molecules (cyclooxygenase 2, CXCL...
A small group of HIV-1-infected subjects who either do not progress to AIDS or progress only slow... more A small group of HIV-1-infected subjects who either do not progress to AIDS or progress only slowly have sustained HIV-1-specific CTL responses. It has been suggested that the specificities of these responses differ from the CTL responses of rapid progressors due to recognition of epitopes that are under structural or functional constraints. We have, in this respect, studied the CTL response to reverse transcriptase (RT) in long term survivors (LTS) and in HIV-1-infected individuals who progressed to AIDS within 3 to 6 yr. Both LTS and progressors displayed vigorous RT-specific CTL responses of comparable magnitude during the asymptomatic phase. From each individual at least two CTL lines were obtained from blood samples drawn at different time points during follow-up. A total of 19 CTL lines recognized nine different RT-derived epitopes. CTL obtained from progressors recognized epitopes with a similar degree of amino acid conservation as epitopes targeted by CTL from LTS. Furthermo...
Advances in Experimental Medicine and Biology, 1995
Major histocompatibility (MHC) class II molecules present peptides derived from exogenous antigen... more Major histocompatibility (MHC) class II molecules present peptides derived from exogenous antigens to CD4+ T lymphocytes (reviewed 1,2,3). The MHC class II molecule is a heterodimer of two transmembrane subunits, an α chain (33 kDa) and β chain (29 kDa), both encoded in the MHC region4. The ends of the peptide-binding groove of MHC class II molecules are open so peptides can extend out. As a result, MHC class II-associated peptides have a length varying between 12–24 amino acids residues5. MHC class II molecules are primarily expressed on antigen presenting cells (APC), such as B cells, macrophages and dendritic cells (DC).
Journal of immunology (Baltimore, Md. : 1950), 1990
C57BL/6 mice are protected from a lethal pneumonia caused by Sendai virus when treated with low d... more C57BL/6 mice are protected from a lethal pneumonia caused by Sendai virus when treated with low doses of mAb directed to the CD3 Ag. The protective mechanism is not due to an accelerated Sendai virus-specific Th cell, CTL, or antibody response but to a strong NK cell response via the in vivo induction of lymphokines. Antibodies directed against the NK1.1 and asialo GM1 marker totally reversed the protective effect of anti-CD3 treatment. In vivo treatment with rIL-2 also induced NK activity and induced antiviral protection. Treatment with anti-CD3 protects when given in a narrow time window (1 day before until 1 day after Sendai virus inoculation), indicating that NK activity is protective in the early phase of virus infection.
Journal of immunology (Baltimore, Md. : 1950), 1997
Bispecific Abs (BsAb) represent a novel format of immunotherapy, recognizing immune effector cell... more Bispecific Abs (BsAb) represent a novel format of immunotherapy, recognizing immune effector cells (e.g., T cells), on the one hand, and target cells (e.g., tumor cells), on the other hand. To be successful, cross-linking of the two cell types is necessary for effector cell activation and subsequent killing of the malignant target cells. We asked the question, whether CTL that were incubated with the BsAb aCD3 x aCD19 and malignant B cells and activated to kill the malignant B cells were still able to eliminate their natural target cells (e.g., virus-infected autologous body cells). To test this, HLA-A*0201-restricted, influenza-specific CTL were incubated with BsAb- and HLA-A*0201-positive B lymphoid tumor cells in combination with HLA-A*0201-positive, virus-infected non-B lymphoid cells as natural target cells. The results showed that even in the presence of BsAb and high amounts of tumor B cells, CTL were still capable of eliminating the virus-infected non-B lymphoid target cells...
Journal of immunology (Baltimore, Md. : 1950), 1996
The impact of the MHC class I peptide binding stability on the immunogenicity of particular pepti... more The impact of the MHC class I peptide binding stability on the immunogenicity of particular peptide Ags in class I-restricted cytotoxic T lymphocyte responses is not clearly established. Therefore, we have determined the dissociation rate of each peptide from MHC class I at 37 degrees C and compared this to that of a consensus CTL epitope. Newly defined immunogenic peptides formed relatively stable MHC-peptide complexes as shown by their low dissociation rates, whereas nonimmunogenic peptides displayed high dissociation rates. In addition virtually all previously described HLA-A*0201-restricted T cell epitopes showed low dissociation rates. Furthermore, we show that the immunogenicity of HIV-1-derived peptides can be predicted more accurately by their dissociation rate than by the MHC class I binding affinity. Selection of peptides based on affinity and their dissociation rate leads to a more precise identification of candidate CTL epitopes than selection based on affinity alone. Th...
High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) th... more High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) that induce and maintain the malignant phenotype. The viral origin of these proteins makes them attractive targets for development of a therapeutic vaccine. Camelid-derived single-domain antibody fragments (nanobodies or VHHs) that recognize cell surface proteins on antigen-presenting cells (APCs) can serve as targeted delivery vehicles for antigens attached to them. Such VHHs were shown to induce CD4+ and CD8+ T-cell responses against model antigens conjugated to them via sortase, but antitumor responses had not yet been investigated. Here, we tested the ability of an anti-CD11b VHH (VHHCD11b) to target APCs and serve as the basis for a therapeutic vaccine to induce CD8+ T cell responses against HPV+ tumors. Mice immunized with VHHCD11b conjugated to an H-2Db-restricted immunodominant E7 epitope (E749-57) had more E7-specific CD8+ T cells compared to those immunized with E749-57 peptide a...
High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) th... more High-risk human papillomavirus-associated cancers express viral oncoproteins (e.g., E6 and E7) that induce and maintain the malignant phenotype. The viral origin of these proteins makes them attractive targets for development of a therapeutic vaccine. Camelid-derived single-domain antibody fragments (nanobodies or VHHs) that recognize cell surface proteins on antigen-presenting cells (APCs) can serve as targeted delivery vehicles for antigens attached to them. Such VHHs were shown to induce CD4+ and CD8+ T-cell responses against model antigens conjugated to them via sortase, but antitumor responses had not yet been investigated. Here, we tested the ability of an anti-CD11b VHH (VHHCD11b) to target APCs and serve as the basis for a therapeutic vaccine to induce CD8+ T cell responses against HPV+ tumors. Mice immunized with VHHCD11b conjugated to an H-2Db-restricted immunodominant E7 epitope (E749-57) had more E7-specific CD8+ T cells compared to those immunized with E749-57 peptide a...
Human papillomavirus (HPV)-mediated suppression of Langerhans cell (LC) function can lead to pers... more Human papillomavirus (HPV)-mediated suppression of Langerhans cell (LC) function can lead to persistent infection and development of cervical intraepithelial neoplasia (CIN). Women with HPV-induced high-grade CIN2/3 have not mounted an effective immune response against HPV, yet it is unknown if LC-mediated T cell activation from such women is functionally impaired against HPV. We investigated the functional activation of in vitro generated LC and their ability to induce HPV16-specific T cells from CIN2/3 patients after exposure to HPV16 followed by treatment with stabilized Poly-I:C (s-Poly-I:C). LC from patients exposed to HPV16 demonstrated a lack of costimulatory molecule expression, inflammatory cytokine secretion, and chemokine-directed migration. Conversely, s-Poly-I:C caused significant phenotypic and functional activation of HPV16-exposed LC, which resulted in de novo generation of HPV16-specific CD8(+) T cells. Our results highlight that LC of women with a history of persis...
Cytokines and Growth Factors in Blood Transfusion, 1997
Effector T cells recognize immunogenic peptides that are presented on the cell membrane in the co... more Effector T cells recognize immunogenic peptides that are presented on the cell membrane in the context of major histocompatibility complex (MHC) molecules. The vast majority of T cells consists of either CD8+ cytotoxic T lymphocytes (CTL) or CD4+ T helper cells. By and large, MHC class I molecules present antigenic peptides to CTL, whereas T helper cells recognize antigenic peptides in the context of MHC class II molecules. These proteins are mainly found on the cells of the immune system with a specialized antigen presenting function. In general, CD4+ lymphocytes secrete cytokines upon triggering that controles the activation of B cells, macrophages and CD8+ cells. MHC class I molecules are expressed on the cell surface of virtually all nucleated cells and present peptides derived from endogenously synthesized proteins to CTL. This enables the CTL to screen almost all cells of the body for antigenic peptides that may be presented as a consequence of viral infection or malignant transformation. Therefore, the CD8+ CTL represent a major effector subset of tumour-specific T cells responsible for rejection of tumours.
The aim of this study was to classify the diversity of anal HPV and non-HPV sexually transmitted ... more The aim of this study was to classify the diversity of anal HPV and non-HPV sexually transmitted infections (STIs) and compare the concordance between anal and genital infections in HIV-infected and uninfected women living in the Tapajós region, Amazon, Brazil. A cross-sectional study was performed with 112 HIV-uninfected and 41 HIV-infected nonindigenous women. Anal and cervical scrapings were collected and analyzed for HPV, Chlamydia trachomatis (CT), Neisseria gonorrheae (NG), Trichomonas vaginalis (TV), Mycoplasma genitalium (MG), and Human alphaherpesvirus 2 (HSV-2). The Kappa test evaluated the concordance between anal and genital infections. The overall prevalence of anal HPV infection was 31.3% in HIV-uninfected and 97.6% in HIV-infected women. The most frequent anal high-risk HPV (hrHPV) types were HPV18 and HPV16 in HIV-uninfected women and HPV51, HPV59, HPV31, and HPV58 in HIV-infected women. Anal HPV75 Betapapillomavirus was also identified. Anal non-HPV STIs were identi...
Human papillomavirus (HPV) entry into epithelial cells is independent of canonical endocytic path... more Human papillomavirus (HPV) entry into epithelial cells is independent of canonical endocytic pathways. Upon interaction with host cells, HPV establishes infection by traversing through an endocytic pathway that is clathrin- and caveolin-independent, but dependent on the annexin A2/S100A10 heterotetramer (A2t). We examined the contribution of monomeric annexin A2 (AnxA2) vs. A2t in HPV infection and endocytosis, and further characterized the role of these molecules in protein trafficking. We specifically show that cell surface A2t is not required for HPV attachment, and in the absence of A2t virion internalization remains clathrin-independent. Without A2t, viral progression from early endosomes to multivesicular endosomes is significantly inhibited, capsid uncoating is dramatically reduced, and lysosomal degradation of HPV is accelerated. Furthermore, we present evidence that AnxA2 forms a complex with CD63, a known mediator of HPV trafficking. Overall, the observed reduction in infe...
Multiple solid cancers contain tertiary lymphoid organs (TLO). However, it is unclear whether the... more Multiple solid cancers contain tertiary lymphoid organs (TLO). However, it is unclear whether they promote tumor rejection, facilitate tumor evasion, or simply whether they are a byproduct of chronic inflammation. We hypothesize that although chronic inflammation induces TLO formation, the tumor milieu can modulate TLO organization and functions in prostate cancer. Therefore, our study seeks to elucidate the cellular and molecular signatures in unique prostatectomy specimens from evanescent carcinoma patients to identify markers of cancer regression, which could be harnessed to modulate local immunosuppression or potentially enhance TLO function. We used multicolor immunofluorescence to stain prostate tissues, collected at different stages of cancer progression (prostatic intraepithelial neoplasia, intermediate and advanced cancer) or from patients with evanescent prostate carcinoma. Tissues were stained with antibodies specific for pro-inflammatory molecules (cyclooxygenase 2, CXCL...
A small group of HIV-1-infected subjects who either do not progress to AIDS or progress only slow... more A small group of HIV-1-infected subjects who either do not progress to AIDS or progress only slowly have sustained HIV-1-specific CTL responses. It has been suggested that the specificities of these responses differ from the CTL responses of rapid progressors due to recognition of epitopes that are under structural or functional constraints. We have, in this respect, studied the CTL response to reverse transcriptase (RT) in long term survivors (LTS) and in HIV-1-infected individuals who progressed to AIDS within 3 to 6 yr. Both LTS and progressors displayed vigorous RT-specific CTL responses of comparable magnitude during the asymptomatic phase. From each individual at least two CTL lines were obtained from blood samples drawn at different time points during follow-up. A total of 19 CTL lines recognized nine different RT-derived epitopes. CTL obtained from progressors recognized epitopes with a similar degree of amino acid conservation as epitopes targeted by CTL from LTS. Furthermo...
Advances in Experimental Medicine and Biology, 1995
Major histocompatibility (MHC) class II molecules present peptides derived from exogenous antigen... more Major histocompatibility (MHC) class II molecules present peptides derived from exogenous antigens to CD4+ T lymphocytes (reviewed 1,2,3). The MHC class II molecule is a heterodimer of two transmembrane subunits, an α chain (33 kDa) and β chain (29 kDa), both encoded in the MHC region4. The ends of the peptide-binding groove of MHC class II molecules are open so peptides can extend out. As a result, MHC class II-associated peptides have a length varying between 12–24 amino acids residues5. MHC class II molecules are primarily expressed on antigen presenting cells (APC), such as B cells, macrophages and dendritic cells (DC).
Journal of immunology (Baltimore, Md. : 1950), 1990
C57BL/6 mice are protected from a lethal pneumonia caused by Sendai virus when treated with low d... more C57BL/6 mice are protected from a lethal pneumonia caused by Sendai virus when treated with low doses of mAb directed to the CD3 Ag. The protective mechanism is not due to an accelerated Sendai virus-specific Th cell, CTL, or antibody response but to a strong NK cell response via the in vivo induction of lymphokines. Antibodies directed against the NK1.1 and asialo GM1 marker totally reversed the protective effect of anti-CD3 treatment. In vivo treatment with rIL-2 also induced NK activity and induced antiviral protection. Treatment with anti-CD3 protects when given in a narrow time window (1 day before until 1 day after Sendai virus inoculation), indicating that NK activity is protective in the early phase of virus infection.
Journal of immunology (Baltimore, Md. : 1950), 1997
Bispecific Abs (BsAb) represent a novel format of immunotherapy, recognizing immune effector cell... more Bispecific Abs (BsAb) represent a novel format of immunotherapy, recognizing immune effector cells (e.g., T cells), on the one hand, and target cells (e.g., tumor cells), on the other hand. To be successful, cross-linking of the two cell types is necessary for effector cell activation and subsequent killing of the malignant target cells. We asked the question, whether CTL that were incubated with the BsAb aCD3 x aCD19 and malignant B cells and activated to kill the malignant B cells were still able to eliminate their natural target cells (e.g., virus-infected autologous body cells). To test this, HLA-A*0201-restricted, influenza-specific CTL were incubated with BsAb- and HLA-A*0201-positive B lymphoid tumor cells in combination with HLA-A*0201-positive, virus-infected non-B lymphoid cells as natural target cells. The results showed that even in the presence of BsAb and high amounts of tumor B cells, CTL were still capable of eliminating the virus-infected non-B lymphoid target cells...
Journal of immunology (Baltimore, Md. : 1950), 1996
The impact of the MHC class I peptide binding stability on the immunogenicity of particular pepti... more The impact of the MHC class I peptide binding stability on the immunogenicity of particular peptide Ags in class I-restricted cytotoxic T lymphocyte responses is not clearly established. Therefore, we have determined the dissociation rate of each peptide from MHC class I at 37 degrees C and compared this to that of a consensus CTL epitope. Newly defined immunogenic peptides formed relatively stable MHC-peptide complexes as shown by their low dissociation rates, whereas nonimmunogenic peptides displayed high dissociation rates. In addition virtually all previously described HLA-A*0201-restricted T cell epitopes showed low dissociation rates. Furthermore, we show that the immunogenicity of HIV-1-derived peptides can be predicted more accurately by their dissociation rate than by the MHC class I binding affinity. Selection of peptides based on affinity and their dissociation rate leads to a more precise identification of candidate CTL epitopes than selection based on affinity alone. Th...
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