Systematic comparison of dendritic cell-based immunotherapeutic strategies for malignant gliomas: in vitro induction of cytolytic and natural killer-like T cells.
OBJECTIVE
To compare the efficacy of various immunotherapeutic strategies of loading dendritic cells (DCs) with whole-glioma cell antigens and characterize the effector responses induced.


METHODS
DCs were either fused with major histocompatibility complex (MHC)-matched glioma cells (Fusion) or pulsed with apoptotic tumor cells (DC/Apo), total tumor ribonucleic acid (RNA) (DC/RNA), or tumor lysate (DC/Lys). These tumor-DC preparations were then assessed for their phenotype, cytokine profile, and capacity to stimulate autologous peripheral blood mononuclear cells (PBMCs) in vitro. Phenotype and tumor-specific cytolytic activities of various effector cell populations were characterized and compared.


RESULTS
The various tumor-DC preparations exhibited similar phenotype and cytokine profiles irrespective of the method of loading tumor-cell antigens. However, the fusion, DC/Apo, and DC/RNA induced superior tumor cytolytic activities in PBMCs compared with DC/Lys or DC and tumor controls. DC/Apo induced the greatest expansion of tumor-specific lymphocytes, as detected by trypan blue exclusion and thymidine incorporation assays. Flow cytometric analyses also revealed the highest relative percentages of T helper cells (CD3+CD4+), cytotoxic T lymphocytes (CTLs) (CD3+CD8+), and natural killer (NK)-like T cells (CD3+CD56+) in the DC/Apo group among all the groups studied, indicating that DC/Apo induced expansion of PBMCs bearing multiple T and NK cell markers. Interestingly, isolated NK-like T cells demonstrated significantly higher tumor cytotoxicity compared with CTLs isolated from the same groups and was also non-MHC-restricted.


CONCLUSIONS
Apoptotic tumor cells may be an optimal source of whole-tumor-cell antigen for immunotherapy of gliomas. The study also demonstrates for the first time that both CTLs and NK-like T cells are expanded and stimulated by mature, tumor-pulsed DCs.
Parajuli
Prahlad
P
Department of Neurosurgery, Wayne State University and Barbara Ann Karmanos Cancer Institute, Detroit, Michigan 48201, USA. pparajuli@med.wayne.edu
Mathupala
Saroj
S
Sloan
Andrew E
AE
D017951:Antigen Presentation / Q000502:physiology; D000951:Antigens, Neoplasm / Q000276:immunology; D001254:Astrocytoma / Q000737:chemistry / Q000628:therapy; D002457:Cell Extracts / Q000276:immunology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000502:physiology; D003713:Dendritic Cells / Q000737:chemistry / Q000502:physiology* / Q000528:radiation effects; D005910:Glioma / Q000737:chemistry / Q000628:therapy*; D006801:Humans; D016130:Immunophenotyping / Q000379:methods; D007167:Immunotherapy / Q000379:methods*; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D019409:Interleukin-15 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000502:physiology; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000502:physiology; D008213:Lymphocyte Activation / Q000502:physiology; D009000:Monocytes / Q000166:cytology / Q000502:physiology; D012334:RNA, Neoplasm / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000502:physiology; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology
D000951:Antigens, Neoplasm; D002457:Cell Extracts; D019409:Interleukin-15; D012334:RNA, Neoplasm; D016753:Interleukin-10; D018664:Interleukin-12