Early membrane potential and cytoplasmic calcium changes during mitogenic stimulation of WEHI 231 cell line by polyene antibiotics, lipopolysaccharide and anti-immunoglobulin.
Changes in free cytosolic calcium concentration and in membrane voltage are thought to be important initiating events in lymphocyte activation. The antifungal agent amphotericin B (AmB) holds interesting immunomodulating properties and its N-thiopropionyl derivative (AmBSH) is a potent polyclonal B-cell activator. These molecules may then exert their stimulating activity through the production of early ionic signals similar to those delivered by the classical activators lipopolysaccharide (LPS) and anti-immunoglobulin (anti-Ig). We addressed this question in a B-cell line (WEHI 231) which has previously been shown to exhibit characteristic response to LPS and anti-Ig. AmBSH protected these cells against anti-Ig-induced cell growth inhibition, providing a LPS-like response. In contrast, the parental compound AmB did not. The two polyene antibiotics did not modify the resting Ca2+i level of the cells, neither did LPS, whereas anti-Ig induced a rapid increase in the cytosolic calcium concentration. On the other hand, polyene antibiotics and LPS promoted membrane depolarization, whereas membrane voltage remained unchanged after anti-Ig treatment. Polyene antibiotics-induced depolarization originated from the increase of membrane permeability to Na+ ions and occurred independently of Ca2+i changes. The relationship between membrane potential and Ca2+i changes in lymphocyte activation are discussed on the basis of these results. Our conclusion was that constitutive Ca2+(-)dependent K+ channels are absent in the WEHI 231 cell line.
Henry-Toulmé
N
N
Laboratoire de Physique et Chimie Biomoléculaire, UA CNRS 198, Université Pierre et Marie Curie, Paris, France.
Sarthou
P
P
Bolard
J
J
D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism*; D004347:Drug Interactions; D007130:Immunoglobulin Idiotypes / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects*; D011090:Polyenes / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D000900:Anti-Bacterial Agents; D007130:Immunoglobulin Idiotypes; D008070:Lipopolysaccharides; D011090:Polyenes; D000666:Amphotericin B; D012964:Sodium; D011188:Potassium; D002118:Calcium