Jf. Katz et Aj. Sant, T-CELL RECEPTOR RECOGNITION OF MHC CLASS-II ALLOANTIGENS IS HIGHLY CELL-TYPE DEPENDENT, The Journal of immunology, 152(4), 1994, pp. 1629-1640
According to some models of T cell education, tolerance, and autoimmun
ity, recognition of MHC molecules by T cells may depend on the nature
of the APC expressing the MHC/Ag complex. To examine this, a panel of
23 I-A(d)-restricted, alloreactive T cells were used to probe MHC clas
s II molecules expressed on established lines representing different l
ineages. Surprisingly, we observed cell type-specific reactivity in th
e majority of the T cells. In all, 18 different reactivity patterns we
re identified. The patterns observed suggests that MHC reactivity can
be organized into a hierarchical pattern for both the APC and the T ce
lls. Experiments assessing T cells' avidities for allogeneic targets,
ability to produce lymphokines, and expression of accessory molecules
revealed no predictive correlation with the hierarchical reactivity pa
ttern, nor did experiments measuring allogeneic target cells' expressi
on of known accessory molecules and ability to stimulate Ag-specific h
ybridomas. These results suggest that the differential reactivity cann
ot be accounted for by accessory molecule discrepancies among the APC,
but rather might reflect deficiencies in the ability of the various A
PC to engage the Ag-specific T cell receptor. Collectively, these data
indicate that a significant fraction of allorecognition of MHC class
II is cell-type dependent and that cell-type-specific recognition may
relate to peptide-specific recognition requirements by the Ag receptor
of alloreactive T cells.