©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
Both Interleukin 4 and Interleukin 13 Induce Tyrosine Phosphorylation of the 140-kDa Subunit of the Interleukin 4 Receptor (*)

(Received for publication, July 8, 1994; and in revised form, November 8, 1994)

Claudia Smerz-Bertling Albert Duschl (§)

From the Theodor-Boveri-Institut für Biowissenschaften, Physiologische Chemie II, Am Hubland, 97074 Würzburg, Germany

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
FOOTNOTES
ACKNOWLEDGEMENTS
REFERENCES

ABSTRACT

We have investigated tyrosine phosphorylation of cellular proteins induced by interleukin (IL) 4 and compared it with the effects of three related cytokines, IL-2, IL-7, and IL-13. We show here that both IL-4 and IL-13 stimulate tyrosine phosphorylation of the 140-kDa IL-4 receptor subunit, which suggests that this receptor protein is used by both cytokines. Receptor phosphorylation induced by IL-13 was both weaker and slower than with IL-4. Stimulation of cells with IL-2 and IL-7 induced identical phosphorylation patterns to each other but not phosphorylation of the 140-kDa IL-4 receptor subunit. The only signal appearing upon stimulation with any of the four cytokines was the weak phosphorylation of an unidentified protein of 160 kDa. SH2 domains of p56 and p59 precipitated the same proteins as anti-phosphotyrosine antibodies after IL-4 stimulation, which suggests that a src-type kinase may be involved in signal transduction through the IL-4 receptor.


INTRODUCTION

Sharing of receptor subunits is an increasingly recognized property of cytokines(1, 2) . One family of growth factors, comprising leukemia inhibiting factor, oncostatin M, ciliary neurotrophic growth factor, IL(^1)-6, and IL-11, uses the gp130 molecule as receptor subunit, while IL-3, IL-5, and GM-CSF share the KH97 receptor protein, also designated betac. A third family of cytokines has emerged with the discovery that IL-4(3, 4) , IL-7(5, 6) , and IL-15 (7) all bind to receptor complexes that contain the subunit of the IL-2 receptor(8) . The IL-2R, a member of the cytokine-type receptor superfamily(8) , has been named c(4, 5) , in analogy to the betac protein of the IL-3/IL-5/GM-CSF group. The same component may also be a part of the receptor for IL-13. Two findings suggest that the receptor for IL-13 shares at least one subunit with the IL-4 receptor: the IL-4 mutant protein Y124D, which inhibits IL-4-dependent reactions(9) , also inhibits effects of IL-13(10, 11) , and IL-13 competes with radiolabeled IL-4 for binding to intact TF-1 cells(10) . It is not clear whether these cytokines share the alpha subunit or the subunit or both.

IL-4 is a pleiotropic immunoregulatory cytokine(12) . Its receptor has at least two subunits, an IL-4 binding receptor protein of 140 kDa (IL-4Ralpha) and the c chain(13) . Specific functions of IL-4 include induction of a T(H)2 phenotype in peripheral T-helper cells (14, 15) and stimulation of IgE synthesis by activated B-cells(16) . Based on size, gene organization, and sequence homologies, IL-13 has been classified as member of a cytokine subgroup designated the IL-4 family(17) . IL-4 and IL-13 have very similar effects on B-cells and monocytes, but in contrast to IL-4, IL-13 cannot stimulate T-cells (18, 19, 20) . It is particularly interesting that IL-13, like IL-4, can induce IgE synthesis by B-cells (18, 21) because this suggests a role for IL-13 in the allergic response.

Transfection of cells with truncated versions of c has shown that its cytoplasmic domain is involved in two different IL-2-induced signaling pathways, one leading to expression of c-fos and c-jun and the other leading to activation of a tyrosine kinase and expression of c-myc(22) . We have compared tyrosine phosphorylation induced by cytokines that have been shown or suggested to use the c subunit. Our results demonstrate that IL-2 and IL-7 have identical effects, while IL-4 and IL-13 induce a second type of phosphorylation pattern. In the course of these studies, we have identified IL-4Ralpha as a substrate of IL-13-dependent tyrosine phosphorylation.


MATERIALS AND METHODS

Cells

Cells were cultured in RFP (RPMI 1640 plus 8% fetal bovine serum, 100 units/ml penicillin, 100 µg/ml streptomycin) at 37 °C and 5% CO(2).

Peripheral blood lymphocytes were obtained from lymphocyte concentrates of healthy blood donors by Ficoll centrifugation. Cells (10^6/ml) were prestimulated with 9 µg/ml PHA (Wellcome Diagnostics, Dartford, UK) for 5 days. The cells were washed twice and incubated two days without PHA before use.

The human pre-myeloid erythroleukemic cell line TF-1 was cultured in RFP containing 100 ng/ml GM-CSF.

The human monocyte-like histiocytic lymphoma U937 was grown in RFP without additions.

The IL-3-dependent murine hematopoietic cell line FDCP-2 (a gift of J. Pierce, Bethesda, MD) was cultured in RFP with 5% of X63 Ag 8-653 BPV-mIL-3-conditioned medium(23) .

Antibodies and Growth Factors

Human IL-2, IL-4, IL-7, and GM-CSF were expressed in Escherichia coli and purified as described(24, 25) . Murine IL-4 was applied as cell supernatant of 3T3-mIL4, a transfected cell line derived from NIH 3T3 (a gift from W. Müller, Köln, Germany). Human IL-13 was obtained from IC Chemicals (München, Germany).

Anti-phosphotyrosine antibodies used were 4G10 (UBI, Lake Placid, NY) for immunoprecipitation and horseradish peroxidase-coupled RC20 (Affiniti, Nottingham, UK) for detection on Western blots. RC20 consists of the bacterially expressed variable regions of the anti-phosphotyrosine antibody PY20, which were mutated for higher affinity(26) . The monoclonal anti-IL-4 receptor antibody A3/10 (27) was a gift from P. Reusch.

The recombinant extracellular domain of the IL-4Ralpha was expressed in Chinese hamster ovary cells (9) and was a gift from S. Arnold.

Generation of SH2 Fusion Proteins

Fusion proteins consisted of the 27-kDa C-terminal fragment of Schistosoma japonicum glutathione S-transferase linked to the SH2 domains of p56 (amino acids 115-240) or p59 (amino acids 137-231). The cDNAs of the SH2 domains were amplified from cDNA derived from PHA-stimulated T-cells by polymerase chain reaction with specific primers that incorporated a 5`-BamHI and a 3`-EcoRI site. Using these sites, the amplified cDNA was cloned into a pGEX-2T vector (Pharmacia LKB Biotechnology Inc., Freiburg, Germany).

The proteins were expressed in E. coli. Cultures of 800 ml with an absorbance of 0.8-1.0 (550 nm) were induced for 3 h with 1 mM isopropyl-1-thio-beta-D-galactopyranoside. Bacteria were lysed, and the fusion proteins were purified as described by Lavan et al.(28) .

Immunoprecipitation and Western Blotting

Cells were incubated for the indicated times with growth factors at 37 °C and 5% CO(2), pelleted, and suspended in ice-cold lysis buffer (50 mM Hepes, pH 7.1, 1.5% Triton X-100, 150 mM NaCl, 1 mM MgCl(2), 10% glycerol, 10 mM Na(4)P(2)O(7), 100 mM NaF, 1 mM Na(3)VO(4), 100 µM Pefabloc, 1 µg/ml aprotinin, 2.5 µg/ml leupeptin, 100 µM antipain, 10 µM pepstatin). Cell lysates were centrifuged at 10.000 times g for 10 min. Cleared supernatants were incubated for 1 h at 4 °C with the anti-IL-4 receptor antibody A3/10 or the anti-phosphotyrosine antibody 4G10, and the immune complexes were collected on protein G-Sepharose for 1 h at 4 °C. In other experiments, the clarified lysates were incubated for 2 h at 4 °C with SH2 fusion proteins bound to glutathione-Sepharose. The immunoprecipitates were washed twice with lysis buffer, twice with 0.5 M LiCl in 100 mM Tris-HCl, pH 8.0, and boiled for 1 min in SDS sample buffer (50 mM Tris-HCl, pH 6.8, 2% SDS, 26 mM dithiothreitol, 10% glycerol). The samples were subjected to SDS-gel electrophoresis on 7.5% gels followed by Western blot analysis with horseradish peroxidase-coupled RC20 (0.1 µg/ml) using an enhanced chemiluminescence detection system (Amersham, Braunschweig).


RESULTS

IL-4, like most other cytokines, induces changes of protein tyrosine phosphorylation in responsive cells(29, 30, 31) . We have compared tyrosine phosphorylation patterns in three human cell types: PHA-stimulated peripheral blood lymphocytes, the erythroleukemic cell line TF-1, and the histiocytic lymphoma U937. The murine myeloid precursor cell line FDCP-2 was used for comparison. When any of the human cell types was stimulated with IL-4, changes in tyrosine phosphorylation were observed (Fig. 1). There was consistently strong phosphorylation of a protein at 140 kDa and, at least in peripheral blood lymphocytes and TF-1 cells, also a weak signal from a protein at 160 kDa. Other changes observed were less reproducible. Stimulation of mouse cells with murine IL-4 induced phosphorylation of several bands, most prominently at 160, 130, 100, and 65 kDa (Fig. 1).


Figure 1: Tyrosine phosphorylation in different cell types after stimulation with IL-4. Human peripheral blood lymphocytes and the human cell lines TF-1 and U937 were stimulated with 100 ng/ml IL-4 for 10 min or left untreated as indicated. The murine cell line FDCP-2 was stimulated with 5% of mIL-4 containing cell supernatant. Cells were lysed, the cleared cell lysates were immunoprecipitated with anti-phosphotyrosine antibody 4G10, and the immune complexes were analyzed by immunoblotting with anti-phosphotyrosine antibody RC20. Lines to the left in this and all other figures indicate positions of marker proteins in kDa, while arrows indicate positions of bands discussed in the text.



When PHA-prestimulated peripheral blood lymphocytes were treated with IL-2 or IL-7, changes in tyrosine phosphorylation were similar but clearly different to the response upon IL-4 (Fig. 2). Both cytokines induced strong phosphorylation of bands at 160 and 85 kDa along with some weaker signals. The kinetics of IL-2- and IL-7-induced phosphorylation were also identical with maximal signals 10 min after stimulation (not shown). The only band appearing with IL-2, IL-4, and IL-7 was the one at 160 kDa, which was weakly phosphorylated in response to all three cytokines.


Figure 2: Tyrosine phosphoproteins after stimulation with IL-2, IL-4, and IL-7 in peripheral blood lymphocytes. Cells were stimulated with 100 ng/ml IL-2, IL-4, or IL-7 for 10 min and lysed; phosphoproteins were analyzed as in Fig. 1.



The cell line TF-1 is dependent on GM-CSF but can also respond to IL-4 and IL-13 with transient proliferation(10, 32) . We used this line to compare the effects of IL-4 and IL-13. Tyrosine phosphorylation after different stimulation times is shown in Fig. 3. IL-4 and IL-13 induced tyrosine phosphorylation of proteins at 160 and 140 kDa. With IL-4, both bands were seen after only 30 s of stimulation. Phosphorylation was maximal after 5-10 min and declined afterwards. Signals obtained with IL-13 were consistently weaker and slower than with IL-4. Both the 160- and the 140-kDa band were detectable after 1-5 min and were maximal after 15 min. The band at 180-190 kDa was sometimes already present in unstimulated cells.


Figure 3: Time course of tyrosine phosphorylation during treatment with IL-4 (A) or IL-13 (B). TF-1 cells were stimulated with 100 ng/ml of IL-4 (A) or IL-13 (B) for the indicated time. Cells were lysed, and phosphoproteins were analyzed as in Fig. 1. In the IL-13 experiment (B), the blot had to be exposed for a longer time during ECL development to obtain acceptable signal strength.



A protein of approximately 140 kDa that has been previously identified as IL-4-dependent phosphorylation substrate in murine cells is IL-4Ralpha (29, 30) . We used the monoclonal antibody A3/10, which was raised against the recombinant extracellular domain of the human IL-4Ralpha (27) to precipitate IL-4Ralpha from stimulated cell lysate. The precipitate was probed with an anti-phosphotyrosine antibody. We found that both in IL-4- and IL-13-stimulated lysates from TF-1 cells the IL-4Ralpha was tyrosine phosphorylated, while no band was obtained from unstimulated cell lysate (Fig. 4A). Competition experiments with the recombinant extracellular domain confirmed that the precipitated protein was the alpha subunit of the IL-4R. These results proved that human IL-4Ralpha is phosphorylated on tyrosine residues in response to both IL-4 and IL-13. The IL-4Ralpha was identified as phosphorylation substrate in peripheral blood lymphocytes as well (Fig. 4B). Tyrosine phosphorylation induced by IL-13 was weaker than with IL-4, regardless whether precipitation was with anti-phosphotyrosine (Fig. 3) or with anti-IL-4Ralpha (Fig. 4A).


Figure 4: Both IL-4 and IL-13 induce tyrosine phosphorylation of the IL-4Ralpha. A, TF-1 cells were stimulated with 100 ng/ml IL-4 or IL-13 for 10 min or left unstimulated. B, peripheral blood lymphocytes (PBL) were stimulated in the same way with IL-4. Both cell types were lysed, and the lysates were immunoprecipitated with antibodies against the IL-4Ralpha in the absence (A, lanes1-3; B, lanes1-2) or presence (A, lanes4-6, B, lanes3 and 4) of the recombinant extracellular domain of the IL-4Ralpha. The precipitates were blotted and probed with the anti-phosphotyrosine antibody RC20.



The identity of the tyrosine kinase phosphorylating IL-4Ralpha is not known. A src-type kinase would be a likely candidate because the IL-2R beta-subunit and the IL-7 receptor complex are associated with p56(33, 34) and p59(35) , respectively. We expressed the SH2 domains of these two kinases as fusion proteins with glutathione S-transferase and used them to precipitate phosphorylated proteins from lysates of IL-2-, IL-4-, and IL-7-stimulated peripheral blood lymphocytes (Fig. 5). The protein patterns precipitated were identical to the ones observed when using the anti-phosphotyrosine antibody 4G10 (Fig. 2). Both lck-SH2 and fyn-SH2 domains precipitated the same proteins.


Figure 5: Binding of cellular phosphoproteins to fusion proteins of glutathione S-transferase (GST) and fyn-SH2 (A) or lck-SH2 (B). Lysates from unstimulated peripheral blood lymphocytes or cells stimulated for 10 min with 100 ng/ml of IL-2, IL-4, or IL-7 were incubated with fyn-SH2 (A) or lck-SH2 fusion proteins (B) bound to glutathione-Sepharose beads. The immune complexes were analyzed by immunoblotting with anti-phosphotyrosine antibody RC20.




DISCUSSION

The pleiotropic and redundant effects displayed by an ever increasing number of identified cytokines make the assignment of specific functions to individual members of the cytokine network a difficult enterprise. Promiscuous receptor subunits may account for some of this complexity. Both cross-competition between cytokines for a receptor and initiation of common signal transduction pathways have to be considered.

IL-4 and IL-13 have very similar functions and share at least one receptor subunit(10, 20) . Data presented in this paper show that IL-4Ralpha is phosphorylated on tyrosine residues following stimulation with either IL-4 or IL-13, which argues for direct participitation of IL-4Ralpha in the IL-13 receptor complex. It has indeed been shown that a monoclonal antibody raised against the extracellular domain of the IL-4Ralpha inhibits IL-4- and IL-13-dependent responses of TF-1 and B-cells(27) . The slower and weaker response observed with IL-13 compared with IL-4 could be due to the unknown specific subunit of the IL-13 receptor, which may result in a lower and limiting number of functional receptors. Another possible explanation could be the use of different src-type kinases by the receptors for IL-4 and IL-13.

Available data therefore prove sharing of IL-4Ralpha between IL-4 and IL-13, but it is not clear whether c is shared as well. Receptors for IL-4 and IL-13 cannot be identical because some IL-4 responsive cells (peripheral T-cells and the SP-B21 cell line) fail to respond to IL-13, presumably because they lack an IL-13-specific receptor subunit (10) . IL-13 does not bind to COS cells transfected with the human IL-4Ralpha, apparently for lack of another receptor component(10) . The molecule lacking is not c because SP-B21 cells fail to bind IL-13, despite the fact that they are IL-4 responsive and must therefore have c(10) . So far, it is not clear whether the IL-13 receptor uses both IL-4Ralpha and c.

IL-4 belongs to the family of cytokines sharing the c chain, and IL-13 is a candidate to this club. To compare signaling pathways within this family, we stimulated peripheral blood lymphocytes with two other interleukins known to use c, IL-2 (8) and IL-7(5, 6) . IL-2 and IL-7 induced tyrosine phosphorylation of the same proteins with identical kinetics. These cytokines seem to be equivalent stimuli for T-cells because extent and kinetics of cell proliferation induced by IL-2 and IL-7 are also very similar to each other but clearly distinct to effects of IL-4(37, 38) .

Only one band, at 160 kDa, appeared to be common to all four cytokines studied here. In mouse cells, a protein of 170 kDa, named 4PS, is strongly phosphorylated in response to IL-4(30, 39) . This protein is related to IRS-1, the major phosphorylation substrate of the insulin receptor, because it cross-reacts weakly with some anti-IRS-1 antibodies(40) , and a cell line deficient in responses to insulin and IL-4 could be reconstituted in both aspects by transfection with IRS-1 (41) . A binding motif for IRS-1 was identified in receptors for insulin, insulin-like growth factor, and the IL-4Ralpha(42) . A highly tyrosine-phosphorylated IRS-1-like protein can therefore be involved in IL-4-induced signal transduction, but it seems to be absent in some IL-4-responsive cell types(13) . The 4PS protein has not yet been further characterized, and neither sequence nor antibodies are available.

In human cells (29) and in murine cells transfected with the human IL-4Ralpha(44) , no phosphorylation in the range of 150-170 kDa has been found. In our hands, murine FDCP-2 cells showed IL-4 induced tyrosine phosphorylation patterns similar to those reported in the literature (30) , including a prominent band at 160 kDa, but the pattern was quite different to those found in human cells (see Fig. 1). The 160-kDa band from human cells appeared at the same molecular weight as the putative 4PS band from FDCP-2 cells, but we hesitate to identify this band as the human homologue of 4PS because the tyrosine phosphorylation observed was much weaker than found in mouse cells and, more importantly, because it also appeared after stimulation with IL-2 and IL-7, which have so far not been suspected to use IRS-1 or 4PS for signal transduction. The 160-kDa band may well represent a signaling element common to the members of the c family, but its identity remains unclear.

It is unclear which tyrosine kinases participate in IL-4-dependent signal transduction. Jak3 is activated by IL-4(45) . A Jak-type kinase probably mediates IL-4-stimulated tyrosine phosphorylation of a transcription factor that binds to sequences resembling the interferon- activation site and increases transcriptional activity in reporter gene assays(46, 47, 48) . IL-13 activates the same transcription factor as IL-4(49) , which may be a consequence of the shared IL-4Ralpha subunit.

Another candidate kinase is a 92-kDa protein found associated with the IL-4 receptor that was recognized by an anti-Fes antibody, which shows that either c-Fes or a closely related protein may be involved in the IL-4 signal transduction pathway(49) . The protein is tyrosine phosphorylated after IL-4 stimulation(50) .

Kinases of the src family could well be involved in IL-4 signaling because p56 binds to IL-2Rbeta and is activated by IL-2 stimulation(33, 34) . Similarly, IL-7 stimulation induces activation of p59 and its binding to the IL-7 receptor complex(35) . We have precipitated phosphorylated proteins from IL-4-stimulated cells with SH2 domains from p56 and p59. Both SH2 domains precipitated similar bands from stimulated cell lysate. A possible explanation is that the precipitated proteins are substrates for src-type kinases, which after phosphorylation can bind to the SH2 domain of the kinase. SH2 domains from different proteins have pronounced specificities, but the binding affinities of SH2 domains from src-type kinases to phosphotyrosine-containing peptides are very similar(51, 52) , so the equivalence of fyn-SH2 and lck-SH2 in our assay is not surprising. Furthermore, it is known that different src-type kinases can be recruited for IL-2 signaling, like p53/56 and p59 in pro-B-cells lacking p56(53, 54) and p59 in cells transfected with an IL-2Rbeta mutant lacking the p56 binding site(55) . Three src-type kinases are expressed in peripheral T-cells, p56, p59, and to a low level p62(43) . We have recently found that yes-SH2 does not bind proteins from PHA blasts after stimulation with IL-2, IL-4, or IL-7. (^2)This suggests that p56 or p59 (or both) may be activated by stimulation of peripheral blood lymphocytes with IL-4, just as in the case of IL-2 and IL-7. Because all three cytokines share the c subunit, activation of src-type kinases could be linked to this common chain.


FOOTNOTES

*
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked ``advertisement'' in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

§
To whom correspondence should be addressed. Tel.: 49-931-888-4117; Fax: 49-931-888-4113; duschl{at}vax.rz.uni-wuerzburg.d400.de.

(^1)
The abbreviations used are: IL, interleukin; betac, common beta subunit of IL-3, IL-5, and GM-CSF; c, common subunit of receptors for IL-2, IL-4, IL-7, and IL-15; IRS-1, insulin receptor substrate 1; PHA, phytohemagglutinin; GM-CSF, granulocyte-macrophage colony-stimulating factor.

(^2)
B. Schnarr, C. Smerz-Bertling, and A. Duschl, unpublished results.


ACKNOWLEDGEMENTS

We thank Drs. W. Sebald and K. Friedrich (Theodor-Boveri-Institut (TBI)) for stimulating discussions. We are also grateful to Drs. J. Pierce (National Institutes of Health) and W. Müller (Institute for Genetics, Köln, Germany) for providing cell lines, P. Reusch (TBI) for anti-IL-4Ralpha antibodies, and S. Arnold (TBI) for the extracellular domain of the IL-4Ralpha. We are indebted to B. Schnarr (TBI) for help with some experiments, to H. Spengler for cell culture work, and to W. Hädelt for oligonucleotide synthesis and DNA sequencing.


REFERENCES

  1. Stahl, N., and Yancopoulos, G. D. (1993) Cell 74, 587-590 [Medline] [Order article via Infotrieve]
  2. Kishimoto, T., Taga, T., and Akira, S. (1994) Cell 76, 253-262 [Medline] [Order article via Infotrieve]
  3. Kondo, M., Takeshita, T., Ishii, N., Nakamura, M., Watanabe, S., Arai, K.-I., and Sugamura, K. (1993) Science 262, 1874-1877 [Medline] [Order article via Infotrieve]
  4. Russell, S. M., Keegan, A. D., Harada, N., Nakamura, Y., Noguchi, M., Leland, P., Friedman, M. C., Miyajima, A., Puri, R. K., Paul, W. E., and Leonard, W. J. (1993) Science 262, 1880-1883 [Medline] [Order article via Infotrieve]
  5. Noguchi, M., Nakamura, Y., Russell, S. M., Ziegler, S. F., Tsang, M., Cao, X., and Leonard, W. J. (1993) Science 262, 1877-1880 [Medline] [Order article via Infotrieve]
  6. Kondo, M., Takeshita, T., Higuchi, M., Nakamura, M., Sudo, T., Nishikawa, S.-I., and Sugamura, K. (1993) Science 263, 1453-1454
  7. Giri, J. G., Ahdieh, M., Eisenman, J., Shanebeck, K., Grabstein, K., Kumaki, S., Namen, A., Park, L. S., Cosman, D., and Anderson, D. (1994) EMBO J. 13, 2822-2830 [Abstract]
  8. Takeshita, T., Asao, H., Ohtani, K., Ishii, N., Kumaki, S., Tanaka, N., Munakata, H., Nakamura, M., and Sugamura, K. (1992) Science 257, 379-382 [Medline] [Order article via Infotrieve]
  9. Kruse. N., Tony, H.-P., and Sebald, W. (1992) EMBO J. 11, 3237-3244 [Abstract]
  10. Zurawski, S. M., Vega, F., Jr., Huyghe, B., and Zurawski, G. (1993) EMBO J. 12, 2663-2670 [Abstract]
  11. Aversa, G., Punnonen, J., Cocks, B. G., de Waal Malefyt, R., Vega, F., Jr., Zurawski, S. M., Zurawski, G., and de Vries, J. E. (1994) J. Exp. Med. 178, 2213-2218 [Abstract]
  12. Paul, W. E. (1991) Blood 77, 1859-1870 [Medline] [Order article via Infotrieve]
  13. Keegan, A. D., and Pierce, J. H. J. (1994) J. Leukocyte Res. 55, 272-279
  14. Mosman, T. R., Cherwinski, H., Bond, M. W., Giedlin, M. A., and Coffman, R. L. (1986) J. Immunol. 136, 2348-2357 [Abstract/Free Full Text]
  15. Romagnani, S. (1991) Immunol. Today 12, 256-257 [Medline] [Order article via Infotrieve]
  16. Coffman, R. L., Ohara, J., Bond, W. M., Carty, J., Zlotnik, A., and Paul, W. E. (1986) J. Immunol. 136, 4538-4541 [Abstract/Free Full Text]
  17. Boulay, J.-L., and Paul, W. E. (1993) Curr. Biol. 3, 573-581
  18. Punnonen, J., Aversa, G., Cocks, B. G., McKenzie, A., N. J., Menon, S., Zurawski, G., de Waal Malefyt, R., and de Vries, J. E. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 3730-3734 [Abstract]
  19. de Waal Malefyt, R., Figdor, C. G., and de Vries, J. E. (1993) Res. Immunol. 144, 629-633 [Medline] [Order article via Infotrieve]
  20. Zurawski, G., and de Vries, J. E. (1994) Immunol. Today 15, 19-26 [CrossRef][Medline] [Order article via Infotrieve]
  21. Defrance, T., Carayon, P., Billian, G., Guillemot, J.-C., Minty, A., Caput, D., and Ferrara, P. (1994) J. Exp. Med. 179, 135-143 [Abstract]
  22. Asao, H., Takeshita, T., Ishii, N., Kumaki, S., Nakamura, M., and Sugamura, K. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 4127-4131 [Abstract]
  23. Karasuyama, H., and Melchers, F. (1988) Eur. J. Immunol. 18, 97-104 [Medline] [Order article via Infotrieve]
  24. Weigel, U., Meyer, M., and Sebald, W. (1989) Eur. J. Biochem. 180, 295-300 [Abstract]
  25. Kruse, N., Lehrnbecher, T., and Sebald, W. (1991) FEBS Lett. 286, 58-60 [CrossRef][Medline] [Order article via Infotrieve]
  26. Ruff-Jamison, S., and Glenney, J. R. (1993) J. Immunol. 150, 3389-3396 [Abstract/Free Full Text]
  27. Tony, H.-P., Shen, B.-J., Reusch, P., and Sebald, W. (1994) Eur. J. Biochem. 225, 659-665 [Abstract]
  28. Lavan, B. E., Kuhné, M. R., Garner, C. W., Anderson, D., Reedijk, M., Pawson, T., and Lienhard, G. E. (1992) J. Biol. Chem. 267, 11631-11636 [Abstract/Free Full Text]
  29. Mire-Sluis, A. R., and Thorpe, R. (1991) J. Biol. Chem. 266, 18113-18118 [Abstract/Free Full Text]
  30. Wang. L.-M., Keegan, A. D., Paul, W. E., Heidaran, M. A., Gutkind, J. S., and Pierce, J. H. (1992) EMBO J. 11, 4899-4908 [Abstract]
  31. Izuhara, K., and Harada, N. (1993) J. Biol. Chem. 268, 13097-13102 [Abstract/Free Full Text]
  32. Kitamura, T., Tange, T., Terasawa, T., Chiba, S., Kuwaki, K., Miyagawa, K., Piao, Y.-F., Miyazano, K., Urabe, A., and Takaku, F. (1989) J. Cell. Physiol. 140, 323-334 [Medline] [Order article via Infotrieve]
  33. Hatakeyama, M., Kono, T., Kobayashi, N., Kawahara, A., Levin, S. D., Perlmutter, R. M., and Taniguchi, T. (1991) Science 252, 1523-1528 [Medline] [Order article via Infotrieve]
  34. Horak, I. D., Gress, R. E., Lucas, P. J., Horak, E. M., Waldmann, T. A., and Bolen, J. B. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 1996-2000 [Abstract]
  35. Venkitaraman, A. R., and Cowling, R. J. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 12083-12087 [Abstract]
  36. Davis, S., Aldrich, T. H., Stahl, N., Pan, L., Taga, T., Kishimoto, T., Ip, N. Y., and Yancopoulos, G. D. (1993) Science 260, 1805-1808 [Medline] [Order article via Infotrieve]
  37. Gatley, M. K., Desai, B. B., Wolitzky, A. G., Quinn, P. M., Dwyer, C. M., Podlaski, F. J., Familletti, P. C., Sinigaglia, F., Chizonnite, R., Gubler, U., and Stern, A. S. (1991) J. Immunol. 147, 874-882 [Abstract/Free Full Text]
  38. Duschl, A., Jahn, U., Bertling, C., and Sebald, W. (1992) Eur. Cytokine Netw. 3, 97-102 [Medline] [Order article via Infotrieve]
  39. Morla, A. O., Schreurs, J., Miyajima, A., and Wang, J. Y. J. (1988) Mol. Cell. Biol. 8, 2214-2218 [Medline] [Order article via Infotrieve]
  40. Wang, L.-M., Keegan, A. D., Li, W., Lienhard, G. E., Pacini, S., Gutkind, J. S., Myers, M. G., Jr., Sun, X.-J., White, M. F., Aaronson, S. A., Paul, W. E., and Pierce, J. H. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 4032-4036 [Abstract]
  41. Wang, L.-M., Myers, M. G., Jr., Sun, X.-J., Aaronson, S. A., White, M., and Pierce, J. H. (1993) Science 261, 1591-1594 [Medline] [Order article via Infotrieve]
  42. Keegan, A. D., Nelms, K., White, M., Wang, L.-M., Pierce, J. H., and Paul, W. E. (1994) Cell 76, 811-820 [Medline] [Order article via Infotrieve]
  43. Perlmutter, R. M., Levin, S. D., Appleby, M. W., Anderson, S. J., and Alberola-Ila, J. (1993) Annu. Rev. Immunol. 11, 451-499 [CrossRef][Medline] [Order article via Infotrieve]
  44. Izuhara, K., Miyajima, A., and Harada, N. (1993) Biochem. Biophys. Res. Commun. 190, 992-1000 [CrossRef][Medline] [Order article via Infotrieve]
  45. Ihle, J. N., Witthuhn, B. A., Quelle, F. W., Yamamoto, K., Thierfelder, W. E., Kreider, B., and Silvennoinen, O. (1994) Trends Biochem. Sci. 19, 222-227 [CrossRef][Medline] [Order article via Infotrieve]
  46. Kotanides, H., and Reich, N. C. (1993) Science 262, 1265-1267 [Medline] [Order article via Infotrieve]
  47. Köhler, I., and Rieber, E. P. (1993) Eur. J. Immunol. 23, 3066-3071 [Medline] [Order article via Infotrieve]
  48. Schindler, C., Kashleva, H., Pernis, A., Pine, R., and Rothman, P. (1994) EMBO J. 13, 1350-1356 [Abstract]
  49. Köhler, I., Alliger, P., Minty, A., Caput, D., Ferrara, P., Höll-Neugebauer, B., Rank, G., and Rieber, E. P. (1994) FEBS Lett. 345, 187-192 [CrossRef][Medline] [Order article via Infotrieve]
  50. Izuhara, K., Feldman, R. A., Greer, P., and Harada, N. (1994) J. Biol. Chem. 269, 18623-18629 [Abstract/Free Full Text]
  51. Songyang, Z., Shoelson, S. E., Chaudhuri, M., Gish, G., Pawson, T., Haser, W. G., King, F., Roberts, T., Ratnofsky, S., Lechleider, R. J., Neel, B. G., Birge, R. B., Fajardo, J. E., Chou, M. M., Hanafusa, H., Schaffhausen, B., and Cantley, L. C. (1993) Cell 72, 767-778 [Medline] [Order article via Infotrieve]
  52. Payne, G., Shoelson, S. E., Gish, G. D., Pawson, T., and Walsh, C. T. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 4902-4906 [Abstract]
  53. Torigoe, T., Saragovi, H. U., and Reed, J. C. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 2674-2678 [Abstract]
  54. Kobayashi, N., Kono, T., Hatakeyama, M., Minami, Y., Miyazawa, T., Perlmutter, R. M., and Taniguchi, T. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 4201-4205 [Abstract]
  55. Shibuya, H., Yoneyama, M., Ninomiya-Tsuji, J., Matsumoto, K., and Taniguchi, T. (1992) Cell 70, 57-67 [Medline] [Order article via Infotrieve]

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