Single cell analysis reveals that IL-4 receptor/Stat6 signaling is not required for the in vivo or in vitro development of CD4+ lymphocytes with a Th2 cytokine profile.
The concept that IL-4 is the primary signal for Th2 lymphocyte differentiation has recently been put in doubt by studies in which the production of Th2-associated cytokines was detected in mice deficient in IL-4 synthesis or IL-4R triggering. In this study, we formally demonstrate by single cell analysis that CD4+ lymphocytes with a classical Th2 phenotype (IL-4+, IL-5+, IFN-gamma-, IL-2-) develop in significant numbers in helminth-infected mice deficient in either IL-4R alpha-chain or Stat6. While an expanded population of Th1 (IL-4-, IL-5-, IFN-gamma+, IL-2+) lymphocytes was observed in the same animals, surprisingly, cells with a mixed Th0 cytokine pattern were rare. The cytokine production phenotypes of the Th1 and Th2 subpopulations generated in infected Stat6-deficient mice were unaffected by in vitro neutralization of endogenous IL-4 or IFN-gamma. Nevertheless, while addition of exogenous rIL-12 resulted in transitory IFN-gamma production by Th2 lymphocytes from both wild-type and Stat6-deficient mice, IL-4 synthesis was preserved in the former, but temporarily ablated in the latter cells. Importantly, IL-4+ IFN-gamma- and IL-4- IFN-gamma+ populations similar to those arising in helminth-infected Stat6-deficient mice could also be generated in vitro by repetitive polyclonal stimulation of CD4+CD62Lhigh lymphocytes from uninfected mice of the same strain. Together, the results of these single cell analysis experiments demonstrate that IL-4R/Stat6 signaling, while influencing the final frequency of Th2 lymphocytes, is not essential for Th2 cell development, and suggest that this pathway has a previously unrecognized function in stabilizing Th2 populations once they have emerged.
Jankovic
D
D
Immunobiology Section, Laboratory of Parasitic Diseases, and Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. djankovic@niaid.nih.gov
Kullberg
M C
MC
Noben-Trauth
N
N
Caspar
P
P
Paul
W E
WE
Sher
A
A
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019948:Receptors, Interleukin-4 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D050800:STAT6 Transcription Factor; D012555:Schistosomiasis mansoni / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D016207:Cytokines; D019948:Receptors, Interleukin-4; D050800:STAT6 Transcription Factor; C494100:Stat6 protein, mouse; D015534:Trans-Activators; D015847:Interleukin-4; D007371:Interferon-gamma