|
|
||||||||
The Journal of Immunology, Vol 155, Issue 3 1411-1419, Copyright © 1995 by American Association of Immunologists
ARTICLES |
MC Bosco, K Pulkki, TK Rowe, AH Zea, T Musso, DL Longo, L Varesio and I Espinoza- Delgado
Laboratory of Experimental Immunology, Inc/DynCorp, NCI-FCRDC, Frederick, MD 21702, USA.
Human monocytes express functional IL-2 receptors (IL-2R) and are directly activated by IL-2 to exert effector and secretory functions. In this study, we show that IL-4 selectively suppressed, in a dose- dependent manner, IL-2-induced monocyte tumoricidal activity, without affecting IFN-gamma-dependent cytotoxicity. This effect was specific because a neutralizing anti-IL-4 mAb completely restored IL-2-activated cytolysis. Furthermore, IL-4 effectively blocked the secretion of proinflammatory cytokines by IL-2-stimulated monocytes. Binding studies with biotin-conjugated IL-2 demonstrated that monocyte stimulation with IL-2 increased IL-2 binding to the cell surface, and that treatment with IL-4 inhibited this augmentation, providing a possible explanation for the decreased responsiveness of monocytes to IL-2 in the presence of IL-4. However, IL-4 suppressive effects could not be ascribed to the down-regulation of the individual components of the IL-2R complex. In fact, co-treatment of monocytes with IL-2 and IL-4 increased the expression of IL-2R gamma chain above the levels induced by IL-2 alone, whereas it did not significantly affect the expression of IL-2R beta chain. Thus, the inhibition of IL-2 binding by IL-4 may be due to the recruitment of the gamma chain into the IL-4-IL-4R system, making it unavailable for participation in the formation of IL-2 binding sites. These findings provide the first evidence of the ability of IL-4 to suppress IL-2-mediated activation of human monocytes and suggest that IL-4 may play an important role in vivo as an inhibitory signal that controls the response of monocytes to IL-2.
This article has been cited by other articles:
![]() |
M. C. Bosco, R. E. Curiel, A. H. Zea, M. G. Malabarba, J. R. Ortaldo, and I. Espinoza-Delgado IL-2 Signaling in Human Monocytes Involves the Phosphorylation and Activation of p59hck 1 J. Immunol., May 1, 2000; 164(9): 4575 - 4585. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. C. Bosco, S. Rottschafer, L. S. Taylor, J. R. Ortaldo, D. L. Longo, and I. Espinoza-Delgado The Antineoplastic Agent Bryostatin-1 Induces Proinflammatory Cytokine Production in Human Monocytes: Synergy With Interleukin-2 and Modulation of Interleukin-2Rgamma Chain Expression Blood, May 1, 1997; 89(9): 3402 - 3411. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |