Immune-mediated Hemolytic Anemia and Thrombocytopenia in a Cat after Bone Marrow Transplantation

A normal 4 kg 3-year-old male mixed breed cat received a bone marrow transplant from an unrelated 2-year-old male donor. Physical examination, complete blood count, serum biochemical profile, and fecal analysis were normal prior to transplantation. The recipient was conditioned for transplantation with marrow ablative (7 Gy; 10 cGy/min) whole body gamma irradiation delivered from a single cobalt-60 source while under inhalant (halothane) anesthesia. Cyclosporine A (CsA) was administered to prevent graft rejection and graft vs. host disease. CsA was administered orally at an initial dose of 40 mg twice a day beginning on day -3 (day 0 = day of transplantation), and continued until day +27; the dose was then reduced to 30 mg twice a day until day +41, 20 mg twice a day until day +48, 15 mg twice a day until day +55 , 10 mg twice a day until day +65, and then discontinued. Bone marrow cells for transplantation were aspirated from the femoral shafts of the anesthetized donor cat. Marrow was harvested 48 hours after irradiation of the recipient by repeated aspirations through 18-gauge bone marrow needles into heparinized syringes and immediately mixed in 10 ml of Hank's balanced salt solution containing 1,500 IU of preservative-free heparin and a trace of DNAase. The marrow suspension was filtered through sterile cotton gauze and administered intravenously to the recipient within 2 hours of collection. A total of 3.1 x lo9 nucleated cells/kg were transplanted. The recipient was maintained in a nonsterile isolation room with water and commercial canned cat food (Kal Kan Foods, Inc., Vernon, CA) fed ad libitum. Supportive care included: subcutaneous administration of trimethoprim-sulfadiazine 2.2 mg/kg twice daily on days + 3 through + 9 when granulocyte count was 300 x 10Y/liter by day +27 (Fig. 1). No clinical abnormalities were noted until 5 days after cessation of CsA treatment (day +70), when the cat developed marked edema of the face and oral mucous membranes, lethargy, anorexia, and polypnea. Rectal temperature was 38.4 C, and auscultation of the thorax revealed no abnormalities. Urinalysis, serum chemistry profile, and complete blood count revealed the following abnormalities: urine was brown and cloudy and 3 + for bilirubin and occult blood; serum albumin 1.9 g/dl, globulin 4.9 g/dl, total bilirubin 2.3 mg/dl, indirect bilirubin 1.5 mg/dl, and potassium 3.7 meq/liter; circulating red blood cell count 2.40 x lo1*/ liter, hematocrit 0.14, reticulocyte count 14%; there were seven nucleated red blood cells per 100 white blood cells, and the platelet count was 1 1 x 1 09//liter. Bone marrow smears were hypercellular with megakaryocyte and erythroid hyperplasia (M/E ratio = 0.3). A positive Coombs test at 37 and 4 C and the demonstration of megakaryocyte autoantibodies detected by direct and indirect immunofluorescence confirmed the diagnosis of immune hemolytic anemia and immune thrombocytopenia.6 The cat was treated with oral prednisolone ( 5 mg twice a day) and CsA (40 mg twice a day). CsA dose was tapered and discontinued after 30 days, and prednisolone dosage was tapered and discontinued after 90 days of treatment. Facial and oral edema and anorexia subsided within 5 days. Red blood cell parameters and platelet count responded favorably after initiation of treatment. Packed cell volume was 0.28,