CD8+ T cell concentration determines their efficiency in killing cognate antigen-expressing syngeneic mammalian cells in vitro and in mouse tissues
Sadna Budhu; John D. Loike; Ashley Pandolfi; Soo Han; Geoffrey Catalano; Andrei Constantinescu; Raphael A. Clynes; Samuel C. Silverstein
- CD8+ T cell concentration determines their efficiency in killing cognate antigen-expressing syngeneic mammalian cells in vitro and in mouse tissues
Loike, John D.
Clynes, Raphael A.
Silverstein, Samuel C.
- Physiology and Cellular Biophysics
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- Journal of experimental medicine
- 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 4,500â€“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 ~3.5 Ã— 105/ml collagen-fibrin gel in vitro and ~3 Ã— 106/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 2 Ã— 107/ml cognate antigen-expressing melanoma cells in collagen fibrin gels is â‰¥107/ml of gel.
- Cellular biology
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