Limits...
Limited transplantation of antigen-expressing hematopoietic stem cells induces long-lasting cytotoxic T cell responses.

Denning WL, Xu J, Guo S, Klug CA, Hel Z - PLoS ONE (2011)

Bottom Line: Continuous antigen presentation by a limited number of differentiated transgenic hematopoietic cells results in an induction and prolonged maintenance of fully functional effector T cell responses in a mouse model.Majority of HSC-induced antigen-specific CD8+ T cells display central memory phenotype, efficiently kill target cells in vivo, and protect recipients against tumor growth in a preventive setting.Furthermore, we confirm previously published observation that high level engraftment of antigen-expressing HSCs following myeloablative conditioning results in tolerance and an absence of specific cytotoxic activity in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.

ABSTRACT
Harnessing the ability of cytotoxic T lymphocytes (CTLs) to recognize and eradicate tumor or pathogen-infected cells is a critical goal of modern immune-based therapies. Although multiple immunization strategies efficiently induce high levels of antigen-specific CTLs, the initial increase is typically followed by a rapid contraction phase resulting in a sharp decline in the frequency of functional CTLs. We describe a novel approach to immunotherapy based on a transplantation of low numbers of antigen-expressing hematopoietic stem cells (HSCs) following nonmyeloablative or partially myeloablative conditioning. Continuous antigen presentation by a limited number of differentiated transgenic hematopoietic cells results in an induction and prolonged maintenance of fully functional effector T cell responses in a mouse model. Recipient animals display high levels of antigen-specific CTLs four months following transplantation in contrast to dendritic cell-immunized animals in which the response typically declines at 4-6 weeks post-immunization. Majority of HSC-induced antigen-specific CD8+ T cells display central memory phenotype, efficiently kill target cells in vivo, and protect recipients against tumor growth in a preventive setting. Furthermore, we confirm previously published observation that high level engraftment of antigen-expressing HSCs following myeloablative conditioning results in tolerance and an absence of specific cytotoxic activity in vivo. In conclusion, the data presented here supports potential application of immunization by limited transplantation of antigen-expressing HSCs for the prevention and treatment of cancer and therapeutic immunization of chronic infectious diseases such as HIV-1/AIDS.

Show MeSH

Related in: MedlinePlus

Antigen-specific CD8+ T cells maintained in HSC-immunized recipients predominantly display central memory phenotype.2×104 HSC-tOVA cells were transplanted into BU-conditioned B6 mice. OVA-specific CD8+ T cells were detected in splenocytes of immunized mice by staining with OVA-specific pentamer and anti-CD8 antibody. Percentages of antigen-specific CD8+ T cells displaying central memory (CD62L+ CD27+) effector memory (CD62L− CD27+), or effector T cell (CD62L− CD27−) phenotypes were determined in the spleens of recipient animals at 2, 4, 12, and 16 weeks post transplantation. Data obtained in two animals per time point are presented.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3040734&req=5

pone-0016897-g003: Antigen-specific CD8+ T cells maintained in HSC-immunized recipients predominantly display central memory phenotype.2×104 HSC-tOVA cells were transplanted into BU-conditioned B6 mice. OVA-specific CD8+ T cells were detected in splenocytes of immunized mice by staining with OVA-specific pentamer and anti-CD8 antibody. Percentages of antigen-specific CD8+ T cells displaying central memory (CD62L+ CD27+) effector memory (CD62L− CD27+), or effector T cell (CD62L− CD27−) phenotypes were determined in the spleens of recipient animals at 2, 4, 12, and 16 weeks post transplantation. Data obtained in two animals per time point are presented.

Mentions: While functional effector memory T cells mediate clearance of tumor and infected cells in vivo, central memory T cells appear to play an indispensible role in the long-term control [1], [32]. To investigate the phenotype of CD8+ T cells elicited by HSC-tOVA immunization, splenic OVA-specific CD8+ T cells were analyzed at 2, 4, 12, and 16 weeks following transplantation of 2×104 HSC-tOVA into BU-pretreated animals. At 2 to 4 weeks post transplantation, antigen-specific CD8+ T cells were distributed between central memory (CD62L+ CD27+) effector memory (CD62L− CD27+), and, to a lesser degree, effector (CD62L− CD27−) T cell populations (Fig. 3). At 16 weeks, more than 70% of OVA-specific CD8+ T cells displayed central memory phenotype. Low production of IL-2, IFN-γ, and granzyme B by OVA-specific memory CD8+ T cells harvested at 12 weeks post immunization was observed by intracellular staining assay following 6 hrs of ex vivo stimulation with specific OVA-1 peptide (data not shown). This observation may be related to the constant antigen stimulation of antigen-specific T cells in vivo.


Limited transplantation of antigen-expressing hematopoietic stem cells induces long-lasting cytotoxic T cell responses.

Denning WL, Xu J, Guo S, Klug CA, Hel Z - PLoS ONE (2011)

Antigen-specific CD8+ T cells maintained in HSC-immunized recipients predominantly display central memory phenotype.2×104 HSC-tOVA cells were transplanted into BU-conditioned B6 mice. OVA-specific CD8+ T cells were detected in splenocytes of immunized mice by staining with OVA-specific pentamer and anti-CD8 antibody. Percentages of antigen-specific CD8+ T cells displaying central memory (CD62L+ CD27+) effector memory (CD62L− CD27+), or effector T cell (CD62L− CD27−) phenotypes were determined in the spleens of recipient animals at 2, 4, 12, and 16 weeks post transplantation. Data obtained in two animals per time point are presented.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040734&req=5

pone-0016897-g003: Antigen-specific CD8+ T cells maintained in HSC-immunized recipients predominantly display central memory phenotype.2×104 HSC-tOVA cells were transplanted into BU-conditioned B6 mice. OVA-specific CD8+ T cells were detected in splenocytes of immunized mice by staining with OVA-specific pentamer and anti-CD8 antibody. Percentages of antigen-specific CD8+ T cells displaying central memory (CD62L+ CD27+) effector memory (CD62L− CD27+), or effector T cell (CD62L− CD27−) phenotypes were determined in the spleens of recipient animals at 2, 4, 12, and 16 weeks post transplantation. Data obtained in two animals per time point are presented.
Mentions: While functional effector memory T cells mediate clearance of tumor and infected cells in vivo, central memory T cells appear to play an indispensible role in the long-term control [1], [32]. To investigate the phenotype of CD8+ T cells elicited by HSC-tOVA immunization, splenic OVA-specific CD8+ T cells were analyzed at 2, 4, 12, and 16 weeks following transplantation of 2×104 HSC-tOVA into BU-pretreated animals. At 2 to 4 weeks post transplantation, antigen-specific CD8+ T cells were distributed between central memory (CD62L+ CD27+) effector memory (CD62L− CD27+), and, to a lesser degree, effector (CD62L− CD27−) T cell populations (Fig. 3). At 16 weeks, more than 70% of OVA-specific CD8+ T cells displayed central memory phenotype. Low production of IL-2, IFN-γ, and granzyme B by OVA-specific memory CD8+ T cells harvested at 12 weeks post immunization was observed by intracellular staining assay following 6 hrs of ex vivo stimulation with specific OVA-1 peptide (data not shown). This observation may be related to the constant antigen stimulation of antigen-specific T cells in vivo.

Bottom Line: Continuous antigen presentation by a limited number of differentiated transgenic hematopoietic cells results in an induction and prolonged maintenance of fully functional effector T cell responses in a mouse model.Majority of HSC-induced antigen-specific CD8+ T cells display central memory phenotype, efficiently kill target cells in vivo, and protect recipients against tumor growth in a preventive setting.Furthermore, we confirm previously published observation that high level engraftment of antigen-expressing HSCs following myeloablative conditioning results in tolerance and an absence of specific cytotoxic activity in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.

ABSTRACT
Harnessing the ability of cytotoxic T lymphocytes (CTLs) to recognize and eradicate tumor or pathogen-infected cells is a critical goal of modern immune-based therapies. Although multiple immunization strategies efficiently induce high levels of antigen-specific CTLs, the initial increase is typically followed by a rapid contraction phase resulting in a sharp decline in the frequency of functional CTLs. We describe a novel approach to immunotherapy based on a transplantation of low numbers of antigen-expressing hematopoietic stem cells (HSCs) following nonmyeloablative or partially myeloablative conditioning. Continuous antigen presentation by a limited number of differentiated transgenic hematopoietic cells results in an induction and prolonged maintenance of fully functional effector T cell responses in a mouse model. Recipient animals display high levels of antigen-specific CTLs four months following transplantation in contrast to dendritic cell-immunized animals in which the response typically declines at 4-6 weeks post-immunization. Majority of HSC-induced antigen-specific CD8+ T cells display central memory phenotype, efficiently kill target cells in vivo, and protect recipients against tumor growth in a preventive setting. Furthermore, we confirm previously published observation that high level engraftment of antigen-expressing HSCs following myeloablative conditioning results in tolerance and an absence of specific cytotoxic activity in vivo. In conclusion, the data presented here supports potential application of immunization by limited transplantation of antigen-expressing HSCs for the prevention and treatment of cancer and therapeutic immunization of chronic infectious diseases such as HIV-1/AIDS.

Show MeSH
Related in: MedlinePlus