COMPOSITION OF TCR-CD3 COMPLEX IN HUMAN INTESTINAL INTRAEPITHELIAL LYMPHOCYTES - LACK OF FC-EPSILON-RI-GAMMA CHAIN

Human intestinal intraepithelial lymphocytes (iIEL) are a unique popul ation of predominantly CD8 alpha beta(+), TCR alpha beta(+) lymphocyte s and, to a lesser extent, TCR gamma delta(+) lymphocytes that prolife rate poorly to anti-CD3 mitogenic signals but display significant cyto lytic activity. Studies in mouse model systems have shown that the gam ma chain of the high-affinity receptor for IgE (Fc epsilon Rly) may su bstitute for the zeta chain in the TCR-CD3 complex of iIEL. This has s uggested that the functional properties of these cells may be associat ed with an altered composition of the TCR-CD3 complex. We therefore an alyzed the TCR-CD3 complex of normal human iIEL. One- and two-dimensio nal non-reducing/reducing SDS-PAGE analysis of CD3 gamma, CD3 delta, C D3 epsilon, zeta and Fc epsilon Rly chain immuno-precipitates of cell surface radiolabeled proteins with subunit-specific antibodies reveale d a TCR-CD3 complex without associated Fc epsilon Rly chains. Thus, no rmal human iIEL contain a TCR-CDS complex that consists predominantly of zeta homodimers in association with the alpha beta TCR and CD3 gamm a, delta and epsilon. Similar to the majority of peripheral lymphocyte s. This indicates that the distinct properties of human ilEL are not a ssociated with substitutions of the Fc epsilon Rly chain in the TCR-CD 3 complex.