TY - JOUR
T1 - Formation of supramolecular activation clusters on fresh ex vivo CD8+ T cells after engagement of the T cell antigen receptor and CD8 by antigen-presenting cells
AU - Potter, T. A.
AU - Grebe, K.
AU - Freiberg, B.
AU - Kupfer, A.
PY - 2001/10/23
Y1 - 2001/10/23
N2 - Upon productive interaction of CD4 T cells with antigen-presenting cells (APCs), receptors and intracellular proteins translocate and form spatially segregated supramolecular activation clusters (SMACs). It is not known whether SMACs are required for CD8 T cell activation. CD8 T cells, unlike CD4 T cells, can be activated by a single peptide-MHC molecule, or by purified monovalent recombinant peptide-MHC molecules. We studied, by three-dimensional digital microscopy, cell conjugates of fresh ex vivo CD8 T cells (obtained from OT-1 mice, which are transgenic for T cell antigen receptor reactive with the complex of H-2Kb and the ovalbumin octapeptide SIINFEKL) and peptide-pulsed APCs. Remarkably, even in T cell:APC conjugates that were formed in the presence of the lowest concentration of peptide that was sufficient to elicit T cell proliferation and IFN-γ production; the θ isoform of protein kinase C was clustered in a central SMAC, and lymphocyte functionassociated antigen 1 and talin were clustered in the peripheral SMAC. Conjugation of T cells to APCs that were pulsed with concentrations of peptide smaller than that required to activate T cells was greatly reduced, and SMACs were not formed at all. APCs expressing mutant H-2Kb (Lys227) molecules that do not bind CD8 were unable to form stable conjugates with these T cells, even at high peptide concentrations. Thus, although CD8 and CD4 T cells may display different sensitivity to the concentration and oligomerization of surface receptors, SMACs are formed and seem to be required functionally in both cell types. However, unlike CD4 T cells, which can form SMACs without CD4, CD8 T cells from OT-1 transgenic mice depend on their coreceptor, CD8, for the proper formation of SMACs.
AB - Upon productive interaction of CD4 T cells with antigen-presenting cells (APCs), receptors and intracellular proteins translocate and form spatially segregated supramolecular activation clusters (SMACs). It is not known whether SMACs are required for CD8 T cell activation. CD8 T cells, unlike CD4 T cells, can be activated by a single peptide-MHC molecule, or by purified monovalent recombinant peptide-MHC molecules. We studied, by three-dimensional digital microscopy, cell conjugates of fresh ex vivo CD8 T cells (obtained from OT-1 mice, which are transgenic for T cell antigen receptor reactive with the complex of H-2Kb and the ovalbumin octapeptide SIINFEKL) and peptide-pulsed APCs. Remarkably, even in T cell:APC conjugates that were formed in the presence of the lowest concentration of peptide that was sufficient to elicit T cell proliferation and IFN-γ production; the θ isoform of protein kinase C was clustered in a central SMAC, and lymphocyte functionassociated antigen 1 and talin were clustered in the peripheral SMAC. Conjugation of T cells to APCs that were pulsed with concentrations of peptide smaller than that required to activate T cells was greatly reduced, and SMACs were not formed at all. APCs expressing mutant H-2Kb (Lys227) molecules that do not bind CD8 were unable to form stable conjugates with these T cells, even at high peptide concentrations. Thus, although CD8 and CD4 T cells may display different sensitivity to the concentration and oligomerization of surface receptors, SMACs are formed and seem to be required functionally in both cell types. However, unlike CD4 T cells, which can form SMACs without CD4, CD8 T cells from OT-1 transgenic mice depend on their coreceptor, CD8, for the proper formation of SMACs.
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U2 - 10.1073/pnas.221458898
DO - 10.1073/pnas.221458898
M3 - Article
C2 - 11606747
AN - SCOPUS:0035940426
SN - 0027-8424
VL - 98
SP - 12624
EP - 12629
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 22
ER -