The Journal of Immunology, Vol 141, Issue 5 1471-1475, Copyright © 1988 by American Association of Immunologists

ARTICLES

T cell-mediated recognition of foreign antigen and the Ia molecule observed by stopped-flow fluorometry

N Utsunomiya, M Nakanishi, Y Arata, T Yasuda, S Saito, K Koyama and T Tadakuma
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.

Th cell-mediated rapid recognition of foreign Ag and the Ia molecule was studied using azobenzenearsonate-L-tyrosine (ABA-L-tyrosine)- specific Th cells (I-Ak restricted), foreign Ag (ABA-L-tyrosine), and APC (H-2k). Initial transmembrane signals in Th cell hybridomas (2-45- 12) and in Th cell lines (A24-17 or A33-7) were monitored by stopped- flow fluorometry with fluorescent probes. It was found that Th cells recognized foreign Ag within 1 s at 25 degrees C on the APC (B10.BR spleen cells or L cells into which I-Ak genes were transferred). Recognition of foreign Ag and the Ia molecule was shown to deliver the initial signals to Th cell hybridomas and T cell lines. First, Th cells had membrane fluidity increased and then calcium was transported from the external medium into the T cells. The initial transmembrane signals to Th cell hybridomas were inhibited by the addition of an anti-I-Ak mAb. None of the initial signals were observed in the absence of either specific foreign Ag or APC.