Past work has shown that a subset of effector T cells with unique characteristics could abrogate hapten- or antigen-induced tolerance, and the reconstitution of this immune response has been termed contrasuppression. We have studied contrasuppression in a model of oral tolerance (OT) in which adoptively transferred antigen-specific T contrasuppressor (Tcs) cells reverse OT and result in antibod...

In the thymus, hematopoietic progenitors commit to the T cell lineage and undergo sequential differentiation to generate diverse T cell subsets, including major histocompatibility complex (MHC)-restricted αβ T cell receptor (TCR) T cells and non-MHC-restricted γδ TCR T cells. The factors controlling precursor commitment and their subsequent maturation and specification into αβ TCR versus γδ TCR...

During T cell activation, T cell receptors (TCR) cluster at the center of the T cell/antigen-presenting cell interface forming a key component of the immunological synapse. The function of this TCR clustering is still unresolved. A comprehensive search for such a function yielded a very limited and specific result. A micrometer-scale receptor clustering integrated the TCR and CD28 signals requi...

T-cell receptor (TCR) triggering results in a cascade of intracellular tyrosine phosphorylation events that ultimately leads to T-cell activation. It is dependent on changes in the relative activities of membrane-associated tyrosine kinases and phosphatases near the engaged TCR. CD45 and CD148 are transmembrane tyrosine phosphatases with large ectodomains that have activatory and inhibitory eff...

The alpha/beta T cell receptor (TCR) recognizes peptide fragments bound in the groove of major histocompatibility complex (MHC) molecules. We modified the TCR alpha chain from a mouse T cell hybridoma and tested its ability to reconstitute TCR expression and function in an alpha chain-deficient variant of the hybridoma. The modified alpha chain differed from wild type only in its leader peptide...

The T cell receptor (TCR)-CD3 complex is composed of a genetically diverse αβ TCR heterodimer associated noncovalently with the invariant CD3 dimers CD3ϵγ, CD3ϵδ, and CD3ζζ. The TCR mediates peptide-MHC recognition, whereas the CD3 molecules transduce activation signals to the T cell. Although much is known about downstream T cell signaling pathways, the mechanism whereby TCR engagement by pept...

The pre-T cell receptor (TCR), which consists of a TCR-beta chain paired with pre-TCR-alpha (pTalpha) and associated with CD3/zeta components, is a critical regulator of T cell development. For unknown reasons, extremely low pre-TCR levels reach the plasma membrane of pre-T cells. By transfecting chimeric TCR-alpha-pTalpha proteins into pre-T and mature T cell lines, we show here that the low s...

Galectin-1 is an endogenous lectin with known T cell immunoregulatory activity, though the molecular basis by which galectin-1 influences Ag specific T cell responses has not been elucidated. Here, we characterize the ability of galectin-1 to modulate TCR signals and responses by T cells with well defined hierarchies of threshold requirements for signaling distinct functional responses. We demo...