Pure red cell aplasia (PRCA) is a kind of anemia characterized by severe reticulocytopenia
and obvious bone marrow erythroblastic cells decreased. Cyclosporine and /or steroids are the
first line therapy but some patients were refractory or intolerance to the treatment. The
effects of the second line therapy are also not satisfactory and sometimes not available. The
investigators aim to explore the efficacy and side-effect of tacrolimus for refractory PRCA.