Enhancement of granulocyte luminescence by murine macrophage secretory products: suggestive evidence for the release of a new activator.
The incubation of macrophages (M phi) in the presence of lipopolysaccharides (LPS) usually results in the release of a variety of immunoregulatory cytokines such as interleukins (IL), tumour necrosis factor (TNF) and colony stimulating factors (CSF). We recently observed that conditioned media (CM) from LPS-treated murine M phi lines probably contain another protein endowed with granulocyte stimulatory activity. This cytokine, which has an apparent MW of about 55 kDa enhances the PMA-induced luminescence of granulocytes and also stimulates their degranulation as measured by lactoferrin release. In contrast to IL1 and IL6 this factor is destroyed by brief treatment at pH 2, but is stable for 60 minutes at 65 degrees C. Unlike CSF, its activity is unchanged by reducing agents such as beta-mercaptoethanol. Furthermore, pretreatment of the M phi with dexamethasone, in order to reduce the release of IL1 and TNF, hardly reduces the effect on granulocyte activation. Finally, treatment with a neutralizing polyclonal anti-murine TNF antiserum only partly abolishes its activity. These results show that, in addition to the already well-described cytokines, LPS-treated murine M phi lines most probably secrete another granulocyte activator.
Willems
J
J
Interdisciplinary Research Center, K. U. Leuven Campus Kortrijk, Belgium.
Leclercq
G
G
Joniau
M
M
D000818:Animals; D001685:Biological Factors / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D015550:Cell Degranulation / Q000187:drug effects; D002460:Cell Line; D016207:Cytokines; D006098:Granulocytes / Q000187:drug effects / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008163:Luminescent Measurements; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight
D001685:Biological Factors; D016207:Cytokines; D008070:Lipopolysaccharides