The goal of the proposed study is to obtain training and experience in immunological research while performing experiments designed to elucidate the interaction of anemia and lymphoid cell perturbations in the ha/ha mutant mouse. Evaluation of this animal model will provide the opportunity for a broadened research environment which can be used to focus on the question of altered lymphopoiesis. Research plan will allow development of expertise in new areas: (1) labeling studies to dissect cellular kinetics (2) use of specific antisera and flow cytometry to analyze subpopulations of cells (3) use of transplantation studies to examine any relationship between erythropoiesis and lymphopoiesis and (4) studies to evaluate the role of NK cells in hemopoietic regulation. Any one of these aspects could offer material for future studies. These experiments will be carried out in laboratories where the techniques are used routinely and under the supervision of well-established individuals in the field. Characterization of this mouse model may provide a resource for studies involving normal lymphopoiesis and the relationship between the immunologic and hematopoietic system.