Interleukin-5 is an autocrine growth factor for Epstein-Barr virus-
transformed B lymphocytes
MA Baumann and CC Paul
Department of Medicine, VA Medical Center, Dayton, OH 45428.
Because of the recent finding that interleukin-5 (IL-5) is produced by
Epstein-Barr virus-transformed B lymphocytes (EBV-B cells), we performed
studies to ascertain whether EBV-B cells might use IL-5 by an autocrine
mechanism. EBV-B cells known to be IL-5 producers were capable of
responding to addition of exogenous IL-5 by dose-related augmented
proliferation. The addition of a neutralizing anti-IL-5 antibody reduced
these effects and also dose-dependently inhibited proliferation and reduced
viability of unsupplemented EBV-B cells, having a maximum effect at about
120 hours. In contrast, no stimulatory effect of IL-5 was noted on
Burkitt's lymphoma cell lines, nor were these lines growth-inhibited by
anti-IL-5 antibody. With biotinylated IL-5, (b-IL-5) second labeling with
streptavidin-FITC, and flow cytometric analysis, binding of IL-5 to EBV-B
cells cultured in fresh medium was demonstrated and could be competed for
by excess unlabeled IL-5, suggesting the presence of IL-5-specific binding
sites. Binding of IL-5 was reduced on cells cultured for longer periods
before study but could be restored by extensively washing cells before
labeling them with b-IL-5, suggesting that surface binding sites had become
occupied by endogenously produced IL-5. These findings support a role for
IL-5 in autocrine support of EBV-B cell growth.
Volume 79,
Issue 7,
pp. 1763-1767,
04/01/1992
Copyright © 1992 by The American Society of Hematology
