Role of IL-2 and IL-4 in exacerbations of murine antigen-induced arthritis.
In this study the roles of different T-cell subsets, and produced cytokines, were investigated in an animal model for acute exacerbations. Flare-up reactions are inducible in the chronic phase of a smouldering antigen-induced inflammation by injection of a small amount of an antigen into a hyper-reactive knee joint. In vivo treatment with anti-CD4 monoclonal antibodies (mAb) almost totally blocked the flare reaction, whereas anti-CD8 treatment did not exert any effect. The role of T-helper 1 (Th1) cells in delayed-type hypersensitivity-resembling diseases is generally entitled proinflammatory, whereas Th2 cells act in an anti-inflammatory manner. To investigate the role of these T-cell subsets in flare-up reactions, anti-interleukin-2 (IL-2) and anti-IL-4 mAb treatments were performed. Anti-IL-2 treatment partly blocked the flare reaction, and anti-IL-4 treatment, although the result was unexpected, blocked the flare more efficiently. Furthermore, when human recombinant IL-2 (hrIL-2) and murine recombinant IL-4 (mrIL-4) were co-injected with the antigen to test their ability respectively to potentiate or down-regulate the flare reaction, both cytokines demonstrated additional pro-inflammatory effects, although hrIL-2 was more potent than mrIL-4. The mere effect of hrIL-2 and mrIL-4 was studied by direct injection into a hyperreactive joint. No flare-up reaction or cell-influx could be induced, suggesting that other mediators are needed to exert pro-inflammatory effects of IL-2 or IL-4. We conclude that not only Th1 cells, but also Th2 lymphocytes (at least regarding IL-4 production) may play a pro-inflammatory role in flare-up reactions of chronic arthritis. Considering therapeutic application of Th2 cell-derived cytokines, one should be aware of the possible pro-inflammatory potential of IL-4.
Jacobs
M J
MJ
Department of Rheumatology, University Hospital Nijmegen, The Netherlands.
van den Hoek
A E
AE
van Lent
P L
PL
van de Loo
F A
FA
van de Putte
L B
LB
van den Berg
W B
WB
D000208:Acute Disease; D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D001168:Arthritis / Q000276:immunology*; D005260:Female; D007114:Immunization; D007376:Interleukin-2 / Q000502:physiology; D015847:Interleukin-4 / Q000502:physiology; D007378:Interleukins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
D000911:Antibodies, Monoclonal; D007376:Interleukin-2; D007378:Interleukins; D015847:Interleukin-4