SVR angiosarcomas can be rejected by CD4 costimulation dependent and CD8 costimulation independent pathways.
OBJECTIVE
We wished to determine whether virally- induced endothelial tumors are rejected by CD4 and CD8 lymphocytes, and whether there are differences in requirements for costimulation in the rejection of these tumors by lymphocyte subsets.


METHODS
We have developed a model of endothelial tumorigenesis through the sequential introduction of SV40 large T antigen and oncogenic H-ras into endothelial cells. These cells (SVR cells) form highly aggressive angiosarcomas in immunocompromised mice, but do not grow in syngeneic C57BL/6 mice. Using both acute blockade with systemic administration of antibodies and mice genetically deficient in the costimulatory molecules CD28, CD40, and CD40L, we have delineated the requirements of costimulation required to reject this virally-induced endothelial tumor.


RESULTS
Control of SVR angiosarcoma is mediated through T lymphocytes, and both CD4 and CD8 lymphocytes are capable of controlling SVR angiosarcoma growth in vivo. Mice genetically deficient in CD28, CD40, and CD40L were able to reject SVR tumors, but depletion of these mice of CD8, but not CD4 cells led to rapid tumor growth. This data suggests that CD4 mediated rejection has a greater dependence of costimulation than CD8 mediated rejection. Surprisingly, acute depletion of costimulatory molecules in immunocompetent C57BL/6 mice led to rapid tumor growth.


CONCLUSIONS
Significant differences exist in the immune status of mice acutely depleted of costimulatory molecules versus genetically deficient mice. Our results suggest that acute depletion is more immunosuppressive than genetic depletion. Humans who undergo costimulatory blockade may require periodic surveillance for virally-induced tumors.
Arbiser
Jack L
JL
Department of Dermatology, Emory University School of Medicine, and Veterans Administration Medical Center, Atlanta, GA 30322, USA. jarbise@emory.edu
Bingaman
Adam
A
Durham
Megan
M
Cowan
Shannon
S
Cohen
Cynthia
C
Zarnegar
Elham
E
Varma
Vijay
V
Larsen
Christian P
CP
D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology; D018106:CD28 Antigens / Q000378:metabolism; D015704:CD4 Antigens / Q000276:immunology*; D019013:CD40 Antigens / Q000378:metabolism; D023201:CD40 Ligand / Q000276:immunology; D016827:CD8 Antigens / Q000276:immunology*; D060908:CTLA-4 Antigen; D006394:Hemangiosarcoma / Q000276:immunology*; D018796:Immunoconjugates; D008214:Lymphocytes / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D016513:Mice, SCID
D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D015704:CD4 Antigens; D019013:CD40 Antigens; D016827:CD8 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D023201:CD40 Ligand; D000069594:Abatacept