Relationship of Ly-3 and idiotypic determinants to the T-cell receptor

Antisera elicited in (C3H x C57BL)F₁ mice by immunization with AKR/Cum thymus cells were found to inhibit the activity of cytotoxic T lymphocytes sensitized either in vivo or in vitro. The contribution of antibodies to either idiotypic or LY-3 determinants was assessed by comparing the activity of the antiserum on cytotoxic T lymphocytes reacting with H-2(b) and H-2(d) target cells, and by absorption experiments.The results indicate that cytotoxic T cells generated in vitro and tested on Con-A blast cells can be inhibited by antibodies against antigenic determinants associated with Ly-3. On the other hand, the inhibition of cytotoxic T cells generated in vivo and tested on tumor target cells required, in addition to Ly-3 antibodies, antibodies directed against idiotypic specificities.