Suppression of Homograft Immunity in Chickens grafted in ovo with Allogeneic Thymus

Abstract

No convincing evidence exists which demonstrates that mammalian thymus cells can directly express their immunological activity. It has been assumed, therefore, that the immunological role of the thymus is an indirect one, that is, that it supplies the ‘executive’ part of the immune machinery of the body with cells the replication of which may well be required to establish normal immune function. Nevertheless, the relationship of thymus cells to the plasma cells as well as to the population of small lymphocytes (which has been considered to be linked with several immune manifestations including tolerance^1,2) is still obscure. A similar concept could be applied to the immunological function of the thymus in birds. However, some observations made in chickens have suggested that cells derived from the thymus might be properly qualified to induce directly an immune response or at least to participate in it^3–7. This report provides some evidence to show that the thymus is capable of inducing a state of tolerance to skin homograft in the chicken.