Addition of bacterial lipopolysaccharide (LPS), a B cell mitogen, to mouse spleen cell cultures strongly stimulated production of colony-stimulating factor (CSF), the humoral regulator of granulopoiesis and macrophage formation in vitro. Splenic-purified lymphocyte generated only small amounts of CSF in response to LPS; however, when a critical number of proteose peptone-stimulated macrophages (about 5 to 10%) was added to the cultures, the ability to secrete LPS-induced CSF was restored. CSF generation in the macrophage-lymphocyte mixed cultures was found to be mediated via a uni-directional pathway whereby LPS-stimulated macrophages secreted lymphostimulatory diffusible factor(s), which replaced intact cells in the cooperative events with lymphocytes. Macrophage potent supernatants activated lymphocytes from congenitally athymic nude mice that, in turn, secreted CSF, indicating that this granulopoietic mediator is probably a lymphokine of B cell origin. The synthetic compound 2-mercaptoethanol could not act as a sufficient substitute for macrophages in generation of CSF in vitro, further pointing to the specific accessory role of macrophages in this secretory process. Macrophages from LPS low responder mice of the strain C3H/HeJ failed to elaborate this lymphostimulatory activity; however, lymphocytes from these mice could be activated to secrete CSF by potent macrophage-derived culture fluids, although to a lesser extent than lymphocytes from LPS high responder mice.
|Number of pages||7|
|Journal||Journal of Immunology|
|State||Published - 1 Jan 1980|
ASJC Scopus subject areas
- Immunology and Allergy