Production of colony-stimulating factors by murine T cells in limiting dilution and long-term cultures.

Abstract

Colony-stimulating factors (CSF) are glycoproteins essential for the formation of colonies of mature haematopoietic cells by single immature progenitor cells (colony-forming cells (CFC)). The number of colonies in semi-solid agar cultures can be used to determine the CSF concentration in biological fluids1. Various murine cells2–6 are able to produce CSF in vitro. Supernatants of spleen cell cultures consisting of a mixture of T cells, B cells and macrophages are found to contain neutrophil-granulocyte–macrophage CSF (GM-CSF), CSF for megakaryocytes (Meg-CSF), eosinophilic granulocytes (Eo-CSF) and erythroid cells (E-CSF)5. The producer cells of these different CSF types, however, have not been defined7. We therefore determined here whether normal T cells produce CSF in vitro and whether GM-CSF, Meg-CSF, Eo-CSF and E-CSF are produced by different T-cell subsets or the progeny of single T-cell clones. Our results indicate that T cells at a high frequency (one out of three) produce CSF at variable amounts even in the absence of accessory cells following mitogen stimulation.