ICAM-1 enhances MHC-peptide activation of CD8(+) T cells without an organized immunological synapse

In addition to the TCR-ligand interaction, other receptor-ligand pairs, suc h as LFA-1 and ICAM-1, play a major role in the activation of T cells. Rece nt studies of T cell activation suggest a coordinated movement of LFA-1 and ICAM-1 in forming a defined zone in the immunological synapse. It is uncle ar from these studies whether the organized molecular geometry of the immun ological synapse is necessary for ICAM-1 enhancement of T cell activation. In this report, we demonstrate that ICAM-1 can enhance the activation of CD 8(+) T cells by MHC-peptide in the absence of an organized immunologic syna pse. Therefore, although the molecular organization of the immunologic syna pse may amplify stimuli, it is not an absolute requirement for either CD8() T cell activation or the ICAIW-1 enhancement of TCR activation.