An analysis of third-party unresponsiveness in immunologically tolerant rats.

Although induced immunological tolerance of histocompatibility antigens is generally considered to be specific, cases of concomitant third-party unresponsiveness may occur. The present paper describes one case in point. Antigenic overlap between original and third-party donor, as well as runt disease have been excluded as possible explanations for the observed lack of specificity. It is hypothesized that an innate inability of the host to respond to the relevant third-party antigen(s), or the ability of certain antigens to induce tolerance of themselves as well as of distinct but related antigens, may be responsible for the phenomenon.