Culture of human T cells in stirred bioreactors for cellular immunotherapyapplications: Shear, proliferation, and the IL-2 receptor

Ex vivo expansion of T cells is a key step of many cellular immunotherapy p rotocols, which require large numbers of immune cells to eradicate malignan t or virally infected cells. The use of stirred culture systems for T cell expansion offers many potential advantages over the static culture systems commonly used today, including homogeneity of culture conditions, ease of s ampling, and implementation of control systems. Primary human T cells as we ll as the transformed TALL103/2 T cell line were cultured in 100-mL spinner flasks as well as 2-L bioreactors to investigate the effects of shear forc es produced by agitation and sparging-based aeration on the expansion of T cells. Primary T cells could be successfully grown at agitation rates of up to 120 rpm in the spinner flasks and to 180 rpm in the bioreactors with no immediate detrimental effects on proliferation. Exposure to agitation and sparging did, however, cause a significantly increased rate of downregulati on of the interleukin-2 receptor (IL-2R), resulting in lower overall expans ion potential from a single stimulation as compared to static controls, wit h faster IL-2R downregulation occurring at higher agitation rates. For the primary T cells, no significant effects of agitation were found on expressi on levels of other key surface receptors (CD3, CD28, or CD62L) examined. No significant effects of agitation were observed on primary T cell metabolis m or levels of cellular apoptosis in the cultures. The TALL103/2 T cell lin e was found to be extremely sensitive to agitation, showing severely reduce d growth at speeds above 30 rpm in 100-mL spinner flasks. This unexpected i ncreased fragility in the transformed T cell line as compared to primary T cells points out the importance of carefully selecting a model cell line wh ich will accurately represent the characteristics of the cell system of int erest. (C) 2000 John Wiley & Sons, Inc.