Interleukin-3-induced downregulation of the expression of interleukin-2
receptor beta chain in human T cells
R Onishi, T Ishikawa, T Kodaka, M Okuma and T Uchiyama
First Division of Internal Medicine, Faculty of Medicine, Kyoto University,
Japan.
We examined the effect of interleukin-3 (IL-3) on human CD4+ cloned T
cells, P607 and 1C2. By flow cytometric analysis, we found that IL-3
downregulated the surface expression of IL-2 receptor (R) beta chain in a
dose-dependent manner but had little effect on that of IL-2R alpha chain. A
simultaneous 125I-labeled IL-2 binding assay showed a decrease in the
number of high-affinity, but not of low-affinity, IL-2Rs by IL- 3. The
downregulation of the IL-2R beta chain began 3 hours after culture
initiation, increased further thereafter, and was completely inhibited by
anti-IL-3 antibodies. Expression of mRNA for either alpha or beta chain was
not reduced by IL-3, and this suggests that the reduction of surface beta
chain expression was not caused by the reduction of beta chain mRNA.
IL-3-accelerating internalization of IL- 2R beta chain appeared to be one
of the mechanisms for IL-3-induced downregulation of surface IL-2R beta
chain expression. IL-3 alone increased the proliferation of T-cell clones
but decreased the existing increment of their proliferation by IL-2.
Accordingly, IL-3 may be one of the factors acting as a liaison between the
hematopoietic and immune systems.
Volume 78,
Issue 11,
pp. 2908-2917,
12/01/1991
Copyright © 1991 by The American Society of Hematology
