Expression of ICOS in vivo defines CD4+ effector T cells with high inflammatory potential and a strong bias for secretion of interleukin 10.
The studies performed to date analyzed the overall participation of the inducible costimulator (ICOS) in model diseases, but did not yield information on the nature and function of ICOS-expressing T cells in vivo. We examined ICOS(+) T cells in the secondary lymphoid organs of nonmanipulated mice, in the context of an "unbiased" immune system shaped by environmental antigens. Using single cell analysis, ICOS(low) cells were found to be loosely associated with the early cytokines interleukin (IL)-2, IL-3, IL-6, and interferon (IFN)-gamma. ICOS(medium) cells, the large majority of ICOS(+) T cells in vivo, were very tightly associated with the synthesis of the T helper type 2 (Th2) cytokines IL-4, IL-5, and IL-13, and these cells exhibited potent inflammatory effects in vivo. In contrast, ICOS(high) T cells were highly and selectively linked to the anti-inflammatory cytokine IL-10. Overall, these data seem to indicate that ICOS cell surface density serves as a regulatory mechanism for the release of cytokines with different immunological properties. Further in vivo functional experiments with in vitro-activated T cells strongly suggested that the ICOS(+) population, although representing in vivo only around 10% of T cells bearing early or late activation markers, nevertheless encompasses virtually all effector T cells, a finding with major diagnostic and therapeutic implications.
Löhning
Max
M
Deutsches Rheumaforschungszentrum, Schumannstrasse 21/22, D-10117 Berlin, Germany.
Hutloff
Andreas
A
Kallinich
Tilmann
T
Mages
Hans Werner
HW
Bonhagen
Kerstin
K
Radbruch
Andreas
A
Hamelmann
Eckard
E
Kroczek
Richard A
RA
D019264:Adoptive Transfer; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis; D066298:In Vitro Techniques; D060889:Inducible T-Cell Co-Stimulator Protein; D007249:Inflammation / Q000209:etiology* / Q000276:immunology; D018836:Inflammation Mediators / Q000378:metabolism; D016753:Interleukin-10 / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D008221:Lymphoid Tissue / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000276:immunology; D010641:Phenotype; D018418:Th2 Cells / Q000276:immunology
D000893:Anti-Inflammatory Agents; D000945:Antigens, Differentiation, T-Lymphocyte; D016207:Cytokines; C556694:Icos protein, mouse; D060889:Inducible T-Cell Co-Stimulator Protein; D018836:Inflammation Mediators; D016753:Interleukin-10; D010047:Ovalbumin