Lymph node cells capable of either primary or secondary antibody responses following transfer to adult normal or x-radiated homologous recipients make no response following transfer to neonatal homologous recipients. On the basis of the present observations it seems that the environment provided by the neonatal recipient is unsuitable for the immunologic activities of transferred cells in the early phases of the immune response. Neonatal recipients can, however, adequately support cells transferred during the process of active antibody formation. These findings suggest that the immunologic inadequacy of the neonatal animal is related to its internal environment and not necessarily to the lack of cells capable of antibody synthesis.
THE NATURE OF THE IMMUNOLOGIC INADEQUACY OF NEONATAL RABBITS AS REVEALED BY CELL TRANSFER STUDIES