A robust automated method to analyze rodent motion during fear conditioning.

A central question in the study of LTP has been to determine what role it plays in memory formation and storage. One valuable form of learning for addressing this issue is associative fear conditioning. In this paradigm an animal learns to associate a tone and shock, such that subsequent presentation of a tone evokes a fear response (freezing behavior).

Generation of T cell help through a MHC class I-restricted TCR.

CD4+ T cells that are activated by a MHC class II/peptide encounter can induce maturation of APCs and promote cytotoxic CD8+ T cell responses. Unfortunately, the number of well-defined tumor-specific CD4+ T cell epitopes that can be exploited for adoptive immunotherapy is limited. To determine whether Th cell responses can be generated by redirecting CD4+ T cells to MHC class I ligands, we have introduced MHC class I-restricted TCRs into postthymic murine CD4+ T cells and examined CD4+ T cell activation and helper function in vitro and in vivo.

Gene transfer of MHC-restricted receptors.

Adoptive therapy with allogeneic or tumor-specific T-cells has shown substantial clinical effects for several human tumors, but the widespread application of this strategy remains a daunting task. The antigen specificity of T-lymphocytes is solely determined by the T-cell receptor (TCR) alpha and beta chains. Consequently, genetic transfer of TCR chains may form an alternative and potentially appealing strategy to impose a desirable tumor-antigen specificity onto cytotoxic or helper T-cell populations.

The impact of self-tolerance on the polyclonal CD8+ T cell repertoire.

TCRs possess considerable cross-reactivity toward structurally related Ags. Because the signaling threshold for negative selection is lower than that required for activation of mature T cells, the question arises as to which extent thymic deletion of self-specific T cells affects T cell responsiveness toward foreign peptides. In this study we show, in three different mouse models systems, that the polyclonal CD8(+) T cell repertoire has a marked ability to react against the majority of Ags related to self despite self-tolerance, even in cases where self and foreign differ only marginally at a single TCR-contact residue.

Contributions of the T cell receptor-associated CD3gamma-ITAM to thymocyte selection.

The immunoreceptor tyrosine-based activation motifs (ITAMs) in the CD3 chains associated with the T cell receptor (TCR) are crucial for TCR signaling. To probe the role of the CD3gamma-ITAM in T cell development, we created knock-in mice in which the CD3gamma chain of the TCR complex is replaced by a mutant signaling-deficient CD3gamma chain, lacking the CD3gamma-ITAM. This mutation results in considerable impairment in positive selection in the polyclonal TCR repertoire.

Specificity and affinity motifs for Grb2 SH2-ligand interactions.

Protein-protein interactions are often mediated by the recognition of short continuous amino acid stretches on target proteins by specific binding domains. Affinity-based selection strategies have successfully been used to define recognition motifs for a large series of such protein domains. However, in many biological systems specificity of interaction may be of equal or greater importance than affinity.