Studies on the Resissance to Tolerance Induction against Human IgG in DDD Mice. V. Insignificant Contribution of Suppressor Cells to the Age-Related Change in Tolerogen Susceptibility

Abstract

Using DDD mice which were shown to aquire tolerogen resistance from 3 to 7 weeks of age, it was investigated whether suppressor cells contributed to the change with age in the tolerance inducibility to human IgG (HGG). Thymus cells from 12-week-old mice were as susceptible as those from 3-week-old mice to tolerance induction against HGG whereas splenic helper T cells of the former were resistant to tolerance induction. This suggests that the age-related change of the tolerogen susceptibility of whole mice may be reflected by that of splenic T cells. Suppressive activity was evaluated in cell transfer experiments and it was shown that spleen cells from either 3-week-old normal or profoundly tolerized mice lacked suppressor activity. Thumus cells from 3-week-old tolerized mice bore suppressive activity which was also shown in normal thymus cells, even in those from aged donors. It was also shown that tolerance inducibility to lymph node cells was not affected by the addition of thymus cells in cell transfer experiments. From the experimental results it was suggested that suppressor cells played little role in tolerance induction to HGG and the age-related increase in the resistance to tolerance inuction was not due to loss of suppressors.