CD8+ T cell concentration determines their efficiency in killing cognate antigen-expressing syngeneic mammalian cells in vitro and in mouse tissues.
We describe a quantitative model for assessing the cytolytic activity of antigen-specific CD8+ T cells in vitro and in vivo in which the concentration of antigen-specific CD8+ T cells determines the efficiency with which these cells kill cognate antigen-expressing melanoma cells in packed cell pellets, in three-dimensional collagen-fibrin gels in vitro, and in established melanomas in vivo. In combination with a clonogenic assay for melanoma cells, collagen-fibrin gels are 4,500-5,500-fold more sensitive than the packed cell pellet-type assays generally used to measure CD8+ T cell cytolytic activity. An equation previously used to describe neutrophil bactericidal activity in vitro and in vivo also describes antigen-specific CD8+ T cell-mediated cytolysis of cognate antigen-expressing melanoma cells in collagen-fibrin gels in vitro and in transplanted tumors in vivo. We have used this equation to calculate the critical concentration of antigen-specific CD8+ T cells, which is the concentration of these cells required to hold constant the concentration of a growing population of cognate antigen-expressing melanoma cells. It is approximately 3.5x10(5)/ml collagen-fibrin gel in vitro and approximately 3x10(6)/ml or /g melanoma for previously published studies of ex vivo-activated adoptively transferred tumor antigen-specific CD8+ T cell killing of cognate antigen-expressing melanoma cells in established tumors in vivo. The antigen-specific CD8+ T cell concentration required to kill 100% of 2x10(7)/ml cognate antigen-expressing melanoma cells in collagen fibrin gels is >or=10(7)/ml of gel.
Budhu
Sadna
S
Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Loike
John D
JD
Pandolfi
Ashley
A
Han
Soo
S
Catalano
Geoffrey
G
Constantinescu
Andrei
A
Clynes
Raphael
R
Silverstein
Samuel C
SC
D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular / Q000235:genetics / Q000276:immunology; D008545:Melanoma / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic
D000951:Antigens, Neoplasm