Aplastic anemia is an immune-mediated disease where bone marrow does not produce sufficient new cells to 
replenish blood cells in the paradigm of the human bone marrow failure syndroms (wikipedia). Hematopoietic stem-cell compartment is the target for the immune response in the pathophysiology concept of Aplastic anemia. The following figure shows the immune destruction of hematopoiesis occured.
Sections such Clinical associations, Pathophysiology of acquired aplastic anemia, Clinical and pathophysiologic relationships among the bone marrow failure syndromes, leukemia, and autoimmune diseases, epidemiology and laboratory identification, Immune-mediated T-cell destruction of marrow, Hematopoiesis, Clonal evolution, Immunosuppression treatment, Management of refractory aplastic anemia, Treatment of moderate pancytopenia, Hematopoietic stem-cell transplantation, Allogenic sibling transplantation for severe aplastic anemia, and stem-cell sources can be seen in the herein document.
Further detailed about Bone Marrow Failure Syndroms can be followed in this Pathophysiology Concept of Aplastic Anemia of pdf filetype (source: aplasticcentral.com)
