Interrelationship between signals transduced by phytohemagglutinin and interleukin 1.
In the murine cell line LBRM-331A5, phytohemagglutinin (PHA) induces secretion of the T cell growth factor interleukin 2 (IL2). IL1 augments PHA-induced IL2 production. In this cell line, PHA stimulates a number of biochemical changes including phospholipid hydrolysis, increases in cytosolic free calcium [( Ca2+]i), membrane hyperpolarization, cytosolic alkalinization, and tyrosine phosphorylation of specific substrates. Using LBRM cells, we have studied the interrelationship between these events and the secretion of IL2. Increases in [Ca2+]i triggered by PHA or following addition of ionomycin result in membrane hyperpolarization but are not required for PHA-induced cytosolic alkalinization or tyrosine phosphorylation. Addition of IL1 to PHA-stimulated cells did not affect any of the biochemical parameters, although it significantly augmented PHA-induced IL2 secretion. Increasing [Ca2+]i with ionomycin did not trigger IL2 secretion, increases in cytosolic pH, or tyrosine phosphorylation in the presence or absence of IL1. Preventing increases in cytosolic pH did not alter PHA-induced changes in [Ca2+]i or membrane potential. These data are compatible with PHA including activation of phospholipase C and production of inositol phosphates resulting in both release of Ca2+ from internal stores and transmembrane uptake of Ca2+ as well as activation of protein kinase C. However, unlike other growth factor or mitogen-stimulated systems, the changes stimulated by PHA and IL1 in LBRM cells including IL2 secretion are not regulated by a pertussis toxin-sensitive G protein.
Oncology Research, Toronto General Hospital, Ontario, Canada.
G B
GB
Mills
M
M
Hill
M
M
McGill
C
C
May
J
J
Stanley
D J
DJ
Stewart
A
A
Mellors
E W
EW
Gelfand
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology*; D007376:Interleukin-2 / Q000096:biosynthesis*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D037342:Pertussis Toxin; D019000:Phosphotyrosine; D010835:Phytohemagglutinins / Q000494:pharmacology*; D015398:Signal Transduction; D017923:Sodium-Hydrogen Exchangers; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D002352:Carrier Proteins; D007295:Inositol Phosphates; D007375:Interleukin-1; D007376:Interleukin-2; D010835:Phytohemagglutinins; D017923:Sodium-Hydrogen Exchangers; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D019000:Phosphotyrosine; D014443:Tyrosine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium