Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Agonist/endogenous peptide–MHC heterodimers drive T cell activation and sensitivity


αβ T lymphocytes are able to detect even a single peptide–major histocompatibility complex (MHC) on the surface of an antigen-presenting cell1,2. This is despite clear evidence, at least with CD4+ T cells, that monomeric ligands are not stimulatory3,4. In an effort to understand how this remarkable sensitivity is achieved, we constructed soluble peptide–MHC heterodimers in which one peptide is an agonist and the other is one of the large number of endogenous peptide–MHCs displayed by presenting cells. We found that some specific combinations of these heterodimers can stimulate specific T cells in a CD4-dependent manner. This activation is severely impaired if the CD4-binding site on the agonist ligand is ablated, but the same mutation on an endogenous ligand has no effect. These data correlate well with analyses of lipid bilayers and cells presenting these ligands, and indicate that the basic unit of helper T cell activation is a heterodimer of agonist peptide– and endogenous peptide–MHC complexes, stabilized by CD4.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Figure 1: Self-peptide–MHCs accumulate at the T cell–APC interface.
Figure 2: Soluble heterodimers of agonist and endogenous pMHCs can stimulate T cells.
Figure 3: Soluble heterodimers can trigger IL-2 production and stimulation by endogenous and agonist pMHC on cell surfaces and lipid bilayers.
Figure 4: T cell sensitivity to mutations affecting CD4 binding and a modified pseudodimer model of activation.


  1. Irvine, D. J., Purbhoo, M. A., Krogsgaard, M. & Davis, M. M. Direct observation of ligand recognition by T cells. Nature 419, 845–849 (2002)

    Article  ADS  CAS  Google Scholar 

  2. Purbhoo, M. A., Irvine, D. J., Huppa, J. B. & Davis, M. M. T cell killing does not require the formation of a stable mature immunological synapse. Nature Immunol. 5, 524–530 (2004)

    Article  CAS  Google Scholar 

  3. Boniface, J. J. et al. Initiation of signal transduction through the T cell receptor requires the multivalent engagement of peptide/MHC ligands. Immunity 9, 459–466 (1998); erratum 9, 891

    Article  CAS  Google Scholar 

  4. Cochran, J. R., Cameron, T. O. & Stern, L. J. The relationship of MHC-peptide binding and T cell activation probed using chemically defined MHC class II oligomers. Immunity 12, 241–250 (2000)

    Article  CAS  Google Scholar 

  5. Tanchot, C., Lemonnier, F. A., Perarnau, B., Freitas, A. A. & Rocha, B. Differential requirements for survival and proliferation of CD8 naive or memory T cells. Science 276, 2057–2062 (1997)

    Article  CAS  Google Scholar 

  6. Ernst, B., Lee, D. S., Chang, J. M., Sprent, J. & Surh, C. D. The peptide ligands mediating positive selection in the thymus control T cell survival and homeostatic proliferation in the periphery. Immunity 11, 173–181 (1999)

    Article  CAS  Google Scholar 

  7. Stefanova, I., Dorfman, J. R. & Germain, R. N. Self-recognition promotes the foreign antigen sensitivity of naive T lymphocytes. Nature 420, 429–434 (2002)

    Article  ADS  CAS  Google Scholar 

  8. Wulfing, C. et al. Costimulation and endogenous MHC ligands contribute to T cell recognition. Nature Immunol. 3, 42–47 (2002)

    Article  CAS  Google Scholar 

  9. Sporri, R. & Reis e Sousa, C. Self peptide/MHC class I complexes have a negligible effect on the response of some CD8 + T cells to foreign antigen. Eur. J. Immunol. 32, 3161–3170 (2002)

    Article  CAS  Google Scholar 

  10. Davis, M. M. et al. Ligand recognition by αβT cell receptors. Annu. Rev. Immunol. 16, 523–544 (1998)

    Article  ADS  CAS  Google Scholar 

  11. Marrack, P., Ignatowicz, L., Kappler, J. W., Boymel, J. & Freed, J. H. Comparison of peptides bound to spleen and thymus class II. J. Exp. Med. 178, 2173–2183 (1993)

    Article  CAS  Google Scholar 

  12. Schild, H. et al. Natural ligand motifs of H-2E molecules are allele specific and illustrate homology to HLA-DR molecules. Int. Immunol. 7, 1957–1965 (1995)

    Article  CAS  Google Scholar 

  13. Lee, S. J., Hori, Y., Groves, J. T., Dustin, M. L. & Chakraborty, A. K. Correlation of a dynamic model for immunological synapse formation with effector functions: two pathways to synapse formation. Trends Immunol. 23, 492–499 (2002)

    Article  CAS  Google Scholar 

  14. Tsien, R. Y. Fluorescent probes of cell signaling. Annu. Rev. Neurosci. 12, 227–253 (1989)

    Article  CAS  Google Scholar 

  15. Li, Q. J. et al. CD4 enhances T cell sensitivity to antigen by coordinating Lck accumulation at the immunological synapse. Nature Immunol. 5, 791–799 (2004)

    Article  CAS  Google Scholar 

  16. Deane, J. A. & Fruman, D. A. Phosphoinositide 3-kinase: diverse roles in immune cell activation. Annu. Rev. Immunol. 22, 563–598 (2004)

    Article  CAS  Google Scholar 

  17. Huppa, J. B., Gleimer, M., Sumen, C. & Davis, M. M. Continuous T cell receptor signaling required for synapse maintenance and full effector potential. Nature Immunol. 4, 749–755 (2003)

    Article  CAS  Google Scholar 

  18. Wettstein, D. A., Boniface, J. J., Reay, P. A., Schild, H. & Davis, M. M. Expression of a class II major histocompatibility complex (MHC) heterodimer in a lipid-linked form with enhanced peptide/soluble MHC complex formation at low pH. J. Exp. Med. 174, 219–228 (1991)

    Article  CAS  Google Scholar 

  19. Schild, H. et al. The nature of major histocompatibility complex recognition by gamma delta T cells. Cell 76, 29–37 (1994)

    Article  CAS  Google Scholar 

  20. Sumen, C., Dustin, M. L. & Davis, M. M. T cell receptor antagonism interferes with MHC clustering and integrin patterning during immunological synapse formation. J. Cell Biol. 166, 579–590 (2004)

    Article  CAS  Google Scholar 

  21. Miceli, M. C. & Parnes, J. R. Role of CD4 and CD8 in T cell activation and differentiation. Adv. Immunol. 53, 59–122 (1993)

    Article  CAS  Google Scholar 

  22. Konig, R., Huang, L. Y. & Germain, R. N. MHC class II interaction with CD4 mediated by a region analogous to the MHC class I binding site for CD8. Nature 356, 796–798 (1992)

    Article  ADS  CAS  Google Scholar 

  23. Cammarota, G. et al. Identification of a CD4 binding site on the β2 domain of HLA-DR molecules. Nature 356, 799–801 (1992)

    Article  ADS  CAS  Google Scholar 

  24. Wu, L. C., Tuot, D. S., Lyons, D. S., Garcia, K. C. & Davis, M. M. Two-step binding mechanism for T-cell receptor recognition of peptide MHC. Nature 418, 552–556 (2002)

    Article  ADS  CAS  Google Scholar 

  25. Delon, J. et al. CD8 expression allows T cell signaling by monomeric peptide-MHC complexes. Immunity 9, 467–473 (1998)

    Article  CAS  Google Scholar 

  26. Ge, Q. et al. Soluble peptide-MHC monomers cause activation of CD8 + T cells through transfer of the peptide to T cell MHC molecules. Proc. Natl Acad. Sci. USA 99, 13729–13734 (2002)

    Article  ADS  CAS  Google Scholar 

  27. Aivazian, D. & Stern, L. J. Phosphorylation of T cell receptor ζ is regulated by a lipid dependent folding transition. Nature Struct. Biol. 7, 1023–1026 (2000)

    Article  CAS  Google Scholar 

  28. Sun, Z. J., Kim, K. S., Wagner, G. & Reinherz, E. L. Mechanisms contributing to T cell receptor signaling and assembly revealed by the solution structure of an ectodomain fragment of the CD3ɛγ heterodimer. Cell 105, 913–923 (2001)

    Article  CAS  Google Scholar 

  29. Krogsgaard, M. et al. Evidence that structural rearrangements and/or flexibility during TCR binding can contribute to T-cell activation. Mol. Cell 12, 1367–1378 (2003)

    Article  CAS  Google Scholar 

  30. Fremont, D. H., Hendrickson, W. A., Marrack, P. & Kappler, J. Structures of an MHC class II molecule with covalently bound single peptides. Science 272, 1001–1004 (1996)

    Article  ADS  CAS  Google Scholar 

Download references


We thank J. D. Stone and L. Stern for providing the crosslinker reagent to initiate these studies as well as for helpful discussions. We thank B. Lillemeier for Baculovirus DNA encoding His-tagged ICAM-1 and B7-1. We thank C. Schæfer-Nielsen, M. Kuhns, A. Krogsgaard and members of the Davis and Chien laboratory for helpful discussions. We thank K. C. Garcia and M. Winslow for critical reading of the manuscript and helpful discussions and analysis. We thank N. Prado and B. Smith for technical assistance. M.K. was a postdoctoral fellow of the Alfred Benzon Foundation and the Danish Medical Research Council. Q.L. and M.H. are supported by Helen Hay Whitney Foundation Fellowships. This work is supported by grants from the NIH and from the Howard Hughes Medical Institute.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Mark M. Davis.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Notes

This file contains legends to accompany Supplementary Figures S1-S7 and Supplementary Movies S1-S5. This file also contains Supplementary Methods and additional References. (DOC 35 kb)

Supplementary Figure S1

Accumulation analysis of endogenous/null MCC-derived peptides. (PDF 1712 kb)

Supplementary Figure S2

Binding and stability analysis of endogenous/null and MCC-derived peptides. (PDF 283 kb)

Supplementary Figure S3

Functional characterization of generated pMHC dimers. SDS-PAGE analysis and T-cell activation (Ca2+) analysis. (PDF 1781 kb)

Supplementary Figure S4

T-cell activation potency (Ca2+ and PI3K) and binding affinity of pMHC dimers. (PDF 358 kb)

Supplementary Figure S5

Effect of endogenous peptides when presented by membrane-associated MHC on the surface of CHO cells or in supported lipid bilayers. (PDF 360 kb)

Supplementary Figure S6

Effect on endogenous-agonist pMHC dimer induced T-cell activation by ablating CD4 binding with a CD4 blocking antibody or CD4 binding mutations. (PDF 216 kb)

Supplementary Figure S7

Effect on null-agonist pMHC dimer induced T-cell activation by ablating CD4 binding with CD4 binding mutations. (PDF 224 kb)

Supplementary Videos S1

Ca2+ response and PH(Akt)-YFP localization in 5C.C7 T cells in response to pMHC dimers. (MOV 416 kb)

Supplementary Videos S2 (MOV 545 kb)

Supplementary Videos S3 (MOV 597 kb)

Supplementary Videos S4 (MOV 458 kb)

Supplementary Videos S5 (MOV 308 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Krogsgaard, M., Li, Qj., Sumen, C. et al. Agonist/endogenous peptide–MHC heterodimers drive T cell activation and sensitivity. Nature 434, 238–243 (2005).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing