OR.72. Enhanced Recognition of Insulin a Chain 1-15 By Expanded T-Cell Clones from Human Type 1 Diabetic (T1D) Pancreatic Draining Lymph Nodes

2006 ◽  
Vol 119 ◽  
pp. S30-S31
Author(s):  
Sally Kent ◽  
David Hafler
2012 ◽  
Vol 209 (2) ◽  
pp. 335-352 ◽  
Author(s):  
David A. Schubert ◽  
Susana Gordo ◽  
Joseph J. Sabatino ◽  
Santosh Vardhana ◽  
Etienne Gagnon ◽  
...  

Recognition of self–peptide-MHC (pMHC) complexes by CD4 T cells plays an important role in the pathogenesis of many autoimmune diseases. We analyzed formation of immunological synapses (IS) in self-reactive T cell clones from patients with multiple sclerosis and type 1 diabetes. All self-reactive T cells contained a large number of phosphorylated T cell receptor (TCR) microclusters, indicative of active TCR signaling. However, they showed little or no visible pMHC accumulation or transport of TCR–pMHC complexes into a central supramolecular activation cluster (cSMAC). In contrast, influenza-specific T cells accumulated large quantities of pMHC complexes in microclusters and a cSMAC, even when presented with 100-fold lower pMHC densities. The self-reactive T cells also maintained a high degree of motility, again in sharp contrast to virus-specific T cells. 2D affinity measurements of three of these self-reactive T cell clones demonstrated a normal off-rate but a slow on-rate of TCR binding to pMHC. These unusual IS features may facilitate escape from negative selection by self-reactive T cells encountering very small amounts of self-antigen in the thymus. However, these same features may enable acquisition of effector functions by self-reactive T cells encountering large amounts of self-antigen in the target organ of the autoimmune disease.


2000 ◽  
Vol 121 (2) ◽  
pp. 275-282 ◽  
Author(s):  
T. K. Kondratieva ◽  
N. V. Kobets ◽  
S. V. Khaidukov ◽  
V. V. Yeremeev ◽  
I. V. Lyadova ◽  
...  

1991 ◽  
Vol 174 (6) ◽  
pp. 1467-1476 ◽  
Author(s):  
D P Gold ◽  
H Offner ◽  
D Sun ◽  
S Wiley ◽  
A A Vandenbark ◽  
...  

This study explores the usage of T cell antigen receptor (TCR) beta chain elements in Lewis rats with experimentally induced allergic encephalomyelitis (EAE). TCRs from 15 different T cell clones and hybridomas derived from animals immunized with myelin basic protein (MBP), and all having specificity for the 21-mer encephalitogenic fragment MBP 68-88, utilized V beta 8.2. In addition, there was a marked conservation of the first two amino acid residues of the junctional complementarity determining region 3 (CDR3) associated with the V beta 8.2 receptors. 12 of 15 contained an aspartic acid followed by serine regardless of the associated J beta element. At the nucleotide level, this conservation of AspSer residues was accomplished with few or no nongermline-encoded nucleotide (N) additions. A similar pattern of AspSer usage and N region nucleotide additions was observed in a number of V beta 8.2 isolates derived from MBP-immunized lymph nodes. In contrast, V beta 8.2 polymerase chain reaction amplified isolates from Lewis T cells activated with concanavalin A or from lymph nodes of complete Freund's adjuvant-immunized animals showed no AspSer utilization (0/31) in the CDR3, and four to nine N region nucleotide additions. We conclude from this finding that AspSer residues in the CDR3, limited N region nucleotide additions, along with V beta 8.2 sequences, contribute to TCR specificity for MBP 68-88. This raises the possibility that encephalitogenic, disease-causing T cells either represent a population that derives from late fetal life or alternatively, that they are rare cells with this particular TCR phenotype contributed to the T cell pool throughout adulthood and are selected by antigen. In either case, the CDR3 AspSer sequences as well as V beta 8.2 sequences are candidates for the receptor target structures recognized by regulator T cells in recovery from and resistance to active EAE. In this respect, a preliminary analysis of TCR utilization in three T cell clones specific for MBP 68-88 isolated from animals recovered from active EAE indicates that while all three use V beta 8.2, only one contains AspSer in the CDR3.


2008 ◽  
Vol 80 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Wânia F. Pereira ◽  
Landi V.C. Guillermo ◽  
Flávia L. Ribeiro-Gomes ◽  
Marcela F. Lopes

Following infection with Leishmania major, T cell activation and apoptosis can be detected in draining lymph nodes of C57BL/6-infected mice. We investigated the mechanisms involved in apoptosis and cytokine expression following Tcellactivation. After two weeks of infection, apoptotic T cells were not detected in draining lymph nodes but activation with anti-CD3 induced apoptosis in both CD4 and CD8 T cells. Treatment with anti-FasLigand, caspase-8 or caspase- 9 inhibitors did not block activation-induced T-cell death. We also investigated whether the blockade of caspase-8 activity would affect the expression of type-1 or type-2 cytokines. At early stages of infection, both CD4 and CD8 T cells expressed IFN-gamma upon activation. Treatment with the caspase-8 inhibitor zIETD-fmk (benzyl-oxycarbonyl-Ile- Glu(OMe)-Thr-Asp(OMe)-fluoromethyl ketone) reduced the proportion of CD8 T cells and IFN-gamma expression in both CD4 and CD8T cells. We conclude that a non apoptotic role of caspase-8 activity may be required for T cell-mediated type-1 responses during L. major infection.


1991 ◽  
Vol 174 (3) ◽  
pp. 583-592 ◽  
Author(s):  
J B Haanen ◽  
R de Waal Malefijt ◽  
P C Res ◽  
E M Kraakman ◽  
T H Ottenhoff ◽  
...  

Mycobacteria elicit a cellular immune response in their hosts. This response usually leads to protective immunity, but may sometimes be accompanied by immunopathology due to delayed type hypersensitivity (DTH). A striking example in man is tuberculoid leprosy, which is characterized by high cellular immunity to Mycobacterium leprae and immunopathology due to DTH. Skin lesions of patients suffering from this disease have the characteristics of DTH reactions in which macrophages and CD4+ T lymphocytes predominate. In animal models, it has been shown that DTH responses are associated with the presence of a particular subset of CD4+ T cells (T helper type 1 [Th1]) that secrete only certain cytokines, such as interleukin 2 (IL-2), interferon gamma (IFN-gamma), and lymphotoxin, but no IL-4 or IL-5. We studied the cytokine release of activated M. leprae-reactive CD4+ T cell clones derived from tuberculoid leprosy patients. These T cell clones, which were reactive with mycobacterial heat shock proteins, exhibited a Th1-like cytokine secretion pattern with very high levels of IFN-gamma. Half of these clones secreted low levels of IL-4 and IL-5, but the ratio of IFN-gamma to IL-4 and IL-5 was much higher than that of T cell clones reactive with nonmycobacterial antigens. A Th1-like cytokine secretion pattern was also observed for T cell clones and polyclonal T cell lines from control individuals that recognized both heat shock and other mycobacterial antigens. The levels of IFN-gamma secreted by these clones were, however, significantly less than those of patient-derived T cell clones. This Th1-like pattern was not found with T cell clones from the same patients and healthy individuals generated in the same manner, but reactive with nonmycobacterial antigens. Our data thus indicate that mycobacteria selectively induce human T cells with a Th1-like cytokine secretion profile.


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