Activation pathways triggered by interleukin-4 in the human plasmacytoma cell line RPMI-8226--differences with resting B lymphocytes.
The early events following the ligation of interleukin-4 (IL-4) to the plasmacytoma cell line RPMI-8226 were analysed as a model of action for this interleukin on differentiated cells of the B lymphocyte lineage. The addition of recombinant IL-4 to these cells resulted in an increase of the intracytoplasmic free calcium concentration [Ca2+]i, but in contrast to normal B cells, this increase was mostly due to a calcium influx rather than to a mobilization from endoplasmic reticulum stores. IL-4 was also found to trigger cAMP accumulation in RPMI-8226 cells, with kinetics similar to that which has been described for normal resting human B lymphocytes. However, in contrast to normal B cells, IL-4 did not increase CD23 membrane expression on RPMI-8226 cells. But after incubation with high concentrations of IL-4, soluble CD23 (sCD23/IgE-BF) could be detected in the supernatant of these cells. In addition, the proliferation of RPMI-8226 cells was only moderately affected by IL-4. The expression of the receptors for IL-6, a growth factor for plasma cells, was not modified upon incubation of these cells with IL-4. These results therefore suggest that terminally differentiating B cells, such as the RPMI-8226 cell line, share common pathways of activation by IL-4 with mature resting B lymphocytes, but differ in some respects.
Lasfar
A
A
U365 INSERM, Institut Curie, Paris, France.
Amirand
C
C
Ballini
J P
JP
Kolb
J P
JP
D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D009101:Multiple Myeloma / Q000097:blood*; D017455:Receptors, IgE / Q000096:biosynthesis; D012016:Reference Values; D015398:Signal Transduction / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D017455:Receptors, IgE; D015847:Interleukin-4; D000242:Cyclic AMP; D002118:Calcium