The Journal of Immunology, Vol 144, Issue 5 1625-1628, Copyright © 1990 by American Association of Immunologists

ARTICLES

Idiotype-specific T helper clones recognize a variable H chain determinant

Y Saeki, JJ Chen, LF Shi, Y Okuda and H Kohler
IDEC Pharmaceuticals Corporation, La Jolla, CA 92037.

Previously we described a Th clone specific for a regulatory idiotype on 3A4, an anti-Id mAb that mimics a murine L1210/GZL tumor-associated Ag. In our studies, we determined the molecular target on the stimulating anti-Id antibody that is recognized by the Th clone. The Th clone responds with proliferation to the H chain of 3A4 but not to the L chain. Furthermore, the 3A4 chain stimulates this Th clone more efficiently than either the intact 3A4 or the Fab fragments, and the presentation by APC of the H chain is more resistant to chloroquine treatment than the presentation of the intact 3A4 molecule. These results suggest that regulatory T cells "see" their target idiotopes as linear sequence determinants present on isolated Ig chains, and show that this might have biologic advantages with respect to the mechanism of Ag presentation.