We will continue our studies of the immunobiology of the laboratory rabbit by investigating the control of the immune response to transplanted normal or neoplastic tissue and the specific modification or abrogation of this response. We will determine the factors involved in the induction of chimeras in neonatal animals using either immunocompetent cells or fibroblastic cells as donor tissue and employ these chimeric animals as a major tool in our proposed research. On the basis of our previous studies we will investigate the genetic and immunologic factors involved in the induction of tolerance to skin grafts, the cellular antigens controlled by the blood group and histocompatibility loci, and specific sub-population of lymphocytes. We are interested in characterizing the antigens of the V2 carcinoma and determining the immunobiological factors involved in the host response to this tumor. We will pursue the identification of the genetic control of the humoral response to passively transferred maternal allotype antigens and we will continue our efforts to develop the rabbit blood group and histocompatibility loci as models for antigen synthess and the control of specificity.