Heterogeneity of soluble T cell products I. Precursor frequency and correlation analysis of cytotoxic and immune interferon (IFN‐γ)‐producing spleen cells in the mouse

Abstract

In this study, the precursor frequency, relationship and activity of murine splenic cytotoxic and immune interferon (IFN-gamma)-producing cells has been determined. C57BL/6 spleen cells were activated by concanavalin A (Con A) and subsequently grown in microcultures under limiting dilution conditions. The progeny of cells plated in microcultures was divided and tested for (a) total cytotoxic activity on EL4 (H-2b) tumor target cells in the presence of Con A to nonspecifically attach the killer to the target cells, and (b) the quantity of IFN-gamma released by Con A stimulation. Cytotoxic T lymphocytes and IFN-gamma-producing cells were present in Con A-activated C57BL/6 spleen cells at a high frequency of approximately 1 out of 3 and 1 out of 2 cells, respectively. IFN-gamma could be released from both noncytotoxic and a large fraction of cytotoxic T cells and the cytotoxic activity was not necessarily associated with IFN-gamma release. In a few selected cultures with a progeny of cells plated at a low cell number (up to 10/well) very high IFN-gamma titers (greater than 10 000 U/ml) could be found. These results provide the first frequency estimate of IFN-producing cells and are discussed with respect to the physiological role of IFN-gamma release from T cells.