These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Two roles for Ia in antigen-specific T cell activation. II. Toward a Velcro model of antigen recognition.
    Author: Kim KH, Thomas DW.
    Journal: J Immunol; 1988 Apr 15; 140(8):2500-7. PubMed ID: 3258611.
    Abstract:
    It has been previously reported that Ia Ag on APC seems to be involved in Ag-specific T cell activation in at least two different ways: one is to associate with foreign Ag to form a neoantigenic determinant (the Ag-specific Ia function), and the second is to interact with T cells in a non-Ag-specific manner. Both Ia functions are required for T cell activation. In the present study we examined whether the T cell structures responsible for the non-Ag-specific Ia interaction were separable from the Ag-specific alpha/beta TCR. Purified protein derivative of tuberculin (PPD)-specific murine hybridoma T cells and polyclonal lymph node T cells were stimulated for IL-2 production by APC pulsed with PPD, glutaraldehyde fixed, and anti-Ia antibody treated, to provide the antigenic PPD/Ia determinant, in the presence of glutaraldehyde-fixed non-Ag-pulsed APC, to provide the non-Ag-specific Ia interactions. However, in several different approaches the T cell structures or activation signals responsible for the Ag-specific recognition and non-Ag-specific Ia interactions seemed to be associated with each other in this experimental system. First, the Ag-specific and non-Ag-specific Ia interactions with T cells were both required simultaneously to initiate T cell activation, and it was not possible to activate T cells by providing either Ia signal subsequent to the other. Second, the T cell structures responsible for the non-Ag-specific Ia interactions appeared to be clonally distributed in PPD-specific lymph node T cells. Third, another T cell hybridoma specific for bovine insulin also showed dual Ia interactions, but the specificity of the non-Ag-specific Ia function was different than that for the PPD-specific T cell response. Fourth, all subclones of PPD-specific T hybridomas that had lost Ag-specific responsiveness also lost functional non-Ag-specific Ia interactions. Taken together, these observations suggest that a single species of TCR may mediate both the Ag-specific and non-Ag-specific Ia interactions. In addition, the non-Ag-specific Ia interaction with T cells augmented the Ag-specific Ia interaction for T cell activation, indicating that both types of interactions may be involved in some T cell responses. Based on these observations, a Velcromodel depicting the synergy between the two Ia functions is proposed in which a matrix of interactions consisting of higher affinity Ag binding and lower affinity Ia-TCR associations provides cooperative sets of signals necessary for cellular activation.
    [Abstract] [Full Text] [Related] [New Search]