Behaviour and fate of transplanted tooth buds: IV. Tolerance induced by tooth buds allografted across the major histocompatibiliity system in rats

The present study tested the hypothesis that skin and tooth bud allografts differ in their ability to induce tolerance to tooth bud. Lewis and Brown Norway (BN) rats (segregated at the major Ag-B histocompatibility locus) were used. Skin or tooth buds were transferred from 10-day-old Lewis rats to young (0-8-day-old) and mature (32- 59-day-old) BN rats. Six weeks later the hosts were further challenged with a second- set tooth bud allograft from a Lewis donor. The evaluation of the second-set grafts, secondary to tooth buds grafted into young hosts, indicated tolerance induction, whereas all the other groups failed to indicate the same. This tends to prove that tissues different in the non-Ag-B system, but similar in their Ag-B system, differ in their ability to induce tolerance. The possibility of adaptation of tooth bud allografts was further investigated in genetically defined rats. However, adaptation was not clearly demonstrated in this study, presumably because of great immunogenetic “distance” between the strains that could have masked the adaptation phenomenon.