Comparison of methods for freezing interleukin-dependent murine cell lines

Various methods for freezing several interleukin-dependent murine cell lines have been compared and were shown to differ in their efficacy from line to line. An interleukin-2-dependent cell line, T572.C5, which was more sensitive to dimethylsulfoxide (DMSO) than the other cell lines, was the most difficult to freeze in a viable state. In order to define better conditions for freezing, the effects of the changes in freezing rates and concentrations of DMSO and of the addition of Ficoll were determined. The optimal freezing rates and DMSO concentrations varied from line to line. The addition of Ficoll increased the viability in some, but not all, cell lines, depending on the freezing conditions used. Thus, the optimal conditions for freezing interleukin-dependent cell lines varied from line to line. In general, the direct freezing procedure was better than the styrofoam-box freezing method. Although programmed freezing under direct temperature control was the most suitable among the freezing procedures examined, unprogrammed procedures also were of practical use.