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Previous Volume 334:630-633 March 7, 1996 Number 10 Next

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Autoimmunity is often implicated in pure red-cell aplasia. Approximately 10 to 15 percent of patients with pure red-cell aplasia have thymomas,¹ and remission of the anemia occurs in 25 to 30 percent of these patients after the thymoma is removed.² In other patients there are immunologic abnormalities, such as hypogammaglobulinemia,³ monoclonal immunoglobulins,⁴ antithyroid antibodies,⁵ antinuclear antibodies,^6,7 and autoimmune hemolytic anemia.^3,8 Immunosuppressive therapy is successful in many patients,^2,9,10,11,12 and a good response to plasmapheresis has been reported in two patients.^13,14

In 1967 Krantz and Kao reported that plasma from a patient with pure red-cell aplasia inhibited heme synthesis by normal bone marrow cells in vitro.⁷ Further studies^4,15,16 demonstrated an IgG antibody against erythroblasts in patients with the disease. More recently, Messner et al.¹⁴ described a patient with a plasma factor that blocked the differentiation of erythroblastic colonies. T cells also appear to be important in the disease,^17,18 and a role for suppressor T cells has been suspected in the form of pure red-cell aplasia that occurs in association with chronic lymphocytic leukemia.^19,20,21

Two patients who may have had a serum inhibitor against erythropoietin have been described.^22,23 However, since these studies were undertaken with unpurified erythropoietin it is difficult to be sure of the specificity of the antibody. We describe a patient with pure red-cell aplasia with antierythropoietin antibodies. These antibodies inhibited the binding of erythropoietin to its receptor and blocked the differentiation of erythroid progenitors in vitro.

Case Report

A 70-year-old woman was admitted to the hospital because of severe anemia. The medical history was notable only for hypertension. There was no history of fever, rash, or exposure to drugs or toxic agents thought to interact with erythrocytes or erythroblasts. The clinical examination was normal, with no organomegaly noted.

The hemoglobin level was 5.7 g per deciliter, with a red-cell count of 1.9 million per cubic millimeter. The mean corpuscular volume was 83.4 µm³, with a mean corpuscular hemoglobin concentration of 28.8 g per deciliter. No reticulocytes were found on several examinations. White-cell and platelet counts were normal. The bone marrow showed pure red-cell aplasia. There were no signs of dysmyelopoiesis or abnormal lymphoid proliferation. Bone marrow cellularity was normal. The granulocytes and megakaryocytes appeared to be normal. Thoracic and abdominal computed tomographic scans showed no evidence of thymoma, lymphoma, or solid tumor.

Serologic tests for the human immunodeficiency virus, cytomegalovirus, hepatitis, and Epstein–Barr virus were negative. Tests for the human B19 parvovirus involving serologic and dot blot analyses and amplification of viral DNA with the polymerase chain reaction were negative.

A direct Coombs' test and a test for antinuclear antibodies were negative. The results of electrophoresis of hemoglobin were normal. Vitamin B₁₂, folate, and creatinine concentrations were normal.

Symptomatic therapy began with the administration of phenotyped, filtered red-cell concentrates. The transfusion requirements were about 4 units of packed red cells per month. The patient declined to receive immunosuppressive therapy.

Nine months after the initial presentation, the reticulocyte count spontaneously increased. The transfusion requirement diminished and was ultimately eliminated after 18 months of observation. As of this writing, the patient is hematologically normal.

Methods

Bone Marrow Cultures

Informed consent was obtained, and the patient's bone marrow was collected in sterile vials containing 200 U of preservative-free heparin. Cells with a density of 1.077 g per cubic centimeter were isolated by Ficoll centrifugation. Erythroid cultures were established according to the plasma-clot culture technique²⁴ with some modifications. The cells were plated at a final concentration of 1 x10⁵ per milliliter in petri dishes (30 by 10 mm) containing alpha medium (Flow Laboratories, ICM, Irvine, Scotland), 1 percent deionized bovine serum albumin (Sigma, St. Louis) prepared according to the methods of McLeod et al.,²⁴ 10 percent l-asparagine (0.2 mg per milliliter; Calbiochem, La Jolla, Calif.) diluted in alpha medium plus calcium chloride (28 mg per deciliter), and 10 percent bovine citrated plasma (GIBCO, Paisley, Scotland). Agar–leukocyte-conditioned medium (10 percent) and various concentrations of recombinant human erythropoietin (Cilag, Paris) were added to the cultures. The clots were fixed at day 7 or day 14 of culture and stained with benzidine and hematoxylin. Granulocytic colonies were grown in methylcellulose medium (0.8 percent methylcellulose in Iscove's medium; Terry Fox Laboratories, Vancouver, B.C., Canada) with 1 percent deionized bovine serum albumin. Agar–leukocyte-conditioned medium at a final concentration of 10 percent and recombinant granulocyte colony-stimulating factor (200 ng per milliliter; Amgen, Thousand Oaks, Calif.) were added to the cultures. Granulocytic colonies were assessed on day 14. Erythroid and granulocytic colonies were grown either with normal pooled serum from 10 healthy volunteers as a control or with the patient's serum at a final concentration of 20 percent. All the cultures were incubated in a fully humidified atmosphere supplemented with 5 percent carbon dioxide. After 7 days of incubation for erythroid colony-forming cells or 14 days for erythroid burst-forming cells, the clots were fixed and stained with benzidine and hematoxylin.

Measurement of Serum Erythropoietin

Serum erythropoietin was measured by enzyme-linked immunosorbent assay with a commercial kit (Bio-Merieux, Marcy l'Etoile, France).

Binding of ¹²⁵I-Labeled Erythropoietin

Highly purified recombinant human erythropoietin, iodinated as previously described,²⁵ had specific activities ranging from 2.5 x 10⁷ to 5 x 10⁷ cpm per microgram. Different concentrations of ¹²⁵I-labeled erythropoietin were incubated overnight at 4°C with 10 µl of the patient's serum or control serum in a total volume of 200 µl of phosphate-buffered saline containing 0.1 percent Triton X-100. Saturating amounts of formalin-fixed Staphylococcus aureus were added, and the tubes were incubated for another 20 minutes while being stirred continuously. Then, 2 ml of ice-cold phosphate-buffered saline containing 0.1 percent Triton X-100 was added, and the tubes were centrifuged for 15 minutes at 1500xg. The resulting pellet was washed twice, and the radioactivity was counted. The same protocol was used for Scatchard analysis, except that at the end of the incubation, the mixture was centrifuged without phosphate-buffered saline and an aliquot of the supernatant was counted to determine free radioactivity.

Deglycosylation Studies

Erythropoietin was deglycosylated as previously described.²⁶ In brief, ¹²⁵I-labeled erythropoietin (0.25 µg) was diluted with 200 µl of 50 mM sodium phosphate buffer (pH 5.0) containing 1 mM phenylmethylsulfonyl fluoride, 1 mM o-phenanthroline, 0.1 percent Triton X-100, and 0.02 percent sodium azide. Then, 50 mU of Arthrobacter ureafaciens neuraminidase was added, and the mixture was incubated for one hour at 37°C. Next, 7.5 mU of O-glycosidase and 500 mU of a mixture of endoglycosidase F and N-glycosidase F (Boehringer–Mannheim, Mannheim, Germany) were added, and the incubation was continued for 18 hours at 37°C. The reaction mixtures then underwent chromatography on Sephadex G25 columns equilibrated with phosphate-buffered saline containing 0.02 percent Tween 20.

Results

The patient's serum erythropoietin level, measured on several occasions at the time of diagnosis, was low for this degree of anemia (5 to 10 mU per milliliter; range in our laboratory in patients without anemia, 5 to 25 mU per milliliter), and the hemoglobin level was between 5.2 and 6.1 g per deciliter. This finding was surprising because serum erythropoietin levels are usually very high in pure red-cell aplasia.¹

Cultures of the patient's bone marrow cells in normal serum yielded normal numbers of erythroid and granulocytic progenitors (erythroid colony-forming cells, erythroid burst-forming cells, and granulocyte–macrophage colony-forming units) (Figure 1). In contrast, when the patient's bone marrow cells were cultured in autologous serum, the growth of erythroid progenitors was completely inhibited, whereas there was no inhibition of granulocytic progenitors (Figure 1). Erythropoietin (1 to 20 U per milliliter) in the culture medium reversed the inhibition of the growth of erythroid progenitors by autologous serum (Figure 1). The same results were obtained when normal bone marrow cells were cultured in the presence of the patient's serum (data not shown).

View larger version (5K): [in this window] [in a new window]   Figure 1. Effect of the Patient's Serum on the Growth of Autologous Hematopoietic Progenitors. In vitro studies were performed at diagnosis. The values are the mean (±SD) numbers of colonies formed. Erythroid progenitors and granulocyte–macrophage colony-forming units (CFU-GM) were cultured with either control serum or the patient's serum at a final concentration of 20 percent in the presence of different concentrations of erythropoietin (1 to 20 U per milliliter) or 200 ng of granulocyte colony-stimulating factor (G-CSF) per milliliter.

 
The results with bone marrow cultures and the serum erythropoietin level suggested the presence of an antibody that was capable of neutralizing erythropoietin. We therefore sought antierythropoietin antibodies in the patient's serum. The patient's serum bound ¹²⁵I-labeled erythropoietin in the presence of formalin-fixed S. aureus, indicating the presence of IgG antierythropoietin antibodies. In contrast, several hundred control serum samples had only background levels of bound ¹²⁵I-labeled erythropoietin. The antierythropoietin antibodies in serum collected at diagnosis were typed with an enzyme-linked immunosorbent assay. The patient's serum or control serum was incubated with erythropoietin-coated microplates, and antierythropoietin antibodies were revealed by class-specific peroxidase-labeled second antibodies (Difco Laboratories, Detroit). With this method, only IgG antierythropoietin antibodies were found in the patient's serum (data not shown). Scatchard analysis of the affinity of the antibodies revealed an apparent single class of ¹²⁵I-labeled erythropoietin–binding sites with a dissociation constant at equilibrium of 430 ± 80 pM (the mean [± SD] of three independent determinations) and a maximal concentration of binding sites of 1.52 ± 0.25 pmol per milliliter of serum (data not shown).

Figure 2 shows that the antibodies bound to fully deglycosylated erythropoietin and thus were directed against the protein moiety of erythropoietin. Precipitation of small amounts of N-deglycosylated erythropoietin in control serum (lanes 9 and 10 of Figure 2) was also observed in the absence of serum (data not shown) and reflects the tendency of N-deglycosylated erythropoietin to aggregate and precipitate.²⁷

View larger version (18K): [in this window] [in a new window]   Figure 2. Immunoprecipitation of Native or Deglycosylated 125I-Labeled Erythropoietin by the Patient's Serum. Native 125I-labeled erythropoietin (lanes 1 and 6) was sequentially deglycosylated with a sialidase alone (lanes 2 and 7), a sialidase and an O-glycosidase (lanes 3 and 8), a mixture of endoglycosidase F and N-glycosidase F (lanes 4 and 9), or the three glycohydrolases together (lanes 5 and 10). Both native and deglycosylated erythropoietin were incubated overnight with the patient's serum (lanes 1 through 5) or control serum (lanes 6 through 10). Then, antibody-bound erythropoietin was recovered with formalin-fixed S. aureus and analyzed by polyacrylamide-gel electrophoresis and autoradiography. The migration positions of unlabeled molecular-mass markers are indicated on the left-hand side of the figure.

 
The patient's serum was tested with UT-7 cells, a human cell line that responds to erythropoietin²⁸ and expresses a large number of erythropoietin receptors.²⁹ Figure 3A and Figure 3B shows that the patient's serum completely inhibited the binding of ¹²⁵I-labeled erythropoietin to UT-7 cells and the erythropoietin-induced proliferation of UT-7 cells.

View larger version (6K): [in this window] [in a new window]   Figure 3. Inhibition of Erythropoietin-Induced Cell Proliferation and 125I-Labeled Erythropoietin Binding to UT-7 Cells by the Patient's Serum. In Panel A, 5000 UT-7 cells were seeded in 120 µl of culture medium containing either 2.5 ng of granulocyte–macrophage colony-stimulating factor (GM-CSF) per milliliter or 0.5 U of erythropoietin per milliliter and the indicated amounts of the patient's serum (x axis). The cells were cultured for three days, and cell proliferation was determined with a fluorescent dye (Alamar blue, Interchim, Montluçon, France). The results are expressed as a percentage of control values in cells cultured without the patient's serum and represent the mean (±SD) values of three determinations. In Panel B, the patient's serum was diluted with normal serum and 20 µl of the mixture containing the indicated amounts of the patient's serum (x axis) was incubated with 40,000 cpm of 125I-labeled erythropoietin for 15 minutes at 37°C. Then, 1 million UT-7 cells were added, and the incubation was continued for another 30 minutes at 37°C. The cells were washed with ice-cold phosphate-buffered saline, and cell-bound radioactivity was measured. Specific binding was determined by subtracting the amount of nonspecific binding measured with the use of a 100-fold molar excess of unlabeled erythropoietin. Each point represents the mean (±SD) of three determinations. The control value of 100 percent specific binding is 6630±590 cpm.

 
In vitro studies of normal marrow cultured with the patient's serum, measurements of the serum erythropoietin level, and quantitation of antierythropoietin antibodies were performed during the evolution of the illness. In vitro inhibition of the growth of erythroid colonies was observed both when the antierythropoietin antibody titer was high and when the serum erythropoietin level was low, at a time when the patient was receiving 4 units of red-cell concentrates per month. Later, the antierythropoietin antibody titer decreased while the serum erythropoietin concentration simultaneously increased; in vitro inhibition of the growth of erythroid colonies was not found. The transfusion requirement decreased, and the reticulocyte count increased sharply (Figure 4A and Figure 4B). Ultimately, antierythropoietin antibodies became undetectable, and the serum erythropoietin concentration, reticulocyte count, and hemoglobin level stabilized at normal values. Transfusions were no longer required.

View larger version (6K): [in this window] [in a new window]   Figure 4. Changes in Hematologic Variables during Follow-up of a Woman with Pure Red-Cell Aplasia. Panel A shows the changes in the antierythropoietin antibody titer, the serum erythropoietin level, and the status of inhibition of erythroid-colony formation in standard culture conditions (erythropoietin concentration, 1 IU per milliliter). A plus sign denotes the presence of inhibition, and a minus sign its absence. Panel B shows the changes in the hemoglobin concentration, reticulocyte count, and transfusion requirements.

 
Discussion

We report finding antierythropoietin antibodies in a patient with pure red-cell aplasia. The presence of antibodies against the protein backbone of the erythropoietin molecule in the patient's serum was ascertained by biologic and biochemical methods. The patient's serum inhibited the growth of erythroid colonies without inhibiting the growth of progenitors of other lineages, and this inhibition was completely reversed by high concentrations of erythropoietin. Moreover, the patient's serum contained an IgG antibody that bound to both native and deglycosylated erythropoietin, inhibited the binding of erythropoietin to the erythropoietin receptor, and blocked the ability of erythropoietin to induce the growth of an erythropoietin-responsive cell line. The concentration of antierythropoietin antibodies in the patient's serum was relatively low, but corresponded to a binding capacity of 2.7 U of erythropoietin per milliliter of serum; the measured equilibrium dissociation constant of the serum antibodies was very low — close to that of the erythropoietin receptor itself.²⁶ This low equilibrium constant strongly suggests that the antibodies were able to neutralize most of the circulating erythropoietin molecules. Indeed, the erythropoietin level in the patient's serum was very low, an unusual finding in pure red-cell aplasia.

Erythroid progenitors, erythroblasts, and erythropoietin are each potential targets of inhibitors of erythropoiesis in acquired pure red-cell aplasia. The high levels of erythropoietin that are usually present in the plasma of patients with the disease indicate that the inhibition is most likely directed at erythroid cells in the marrow, and several studies have reported the presence of IgG antibodies against erythroblasts or erythropoietin-responsive cells.^4,15,16 Two unusual cases of pure red-cell aplasia and low serum erythropoietin levels have been described. In 1968, Jepson and Lowenstein²² raised the possibility of an antierythropoietin inhibitor in one case of pure red-cell aplasia, but the means of testing their idea were not available. In 1975 Peschle et al.²³ described a patient they suspected of having antierythropoietin antibodies. The administration of this patient's IgG to mice induced severe anemia without increasing erythropoietin levels. Before therapy, no erythropoietin activity was detectable in the patient's serum. After acidification and boiling of the serum to denature the IgG, the erythropoietin activity increased greatly. However, since purified erythropoietin was not available, a direct demonstration of antierythropoietin antibodies was not possible.

The course of the pure red-cell aplasia in our patient mimics the evolution of transient erythroblastopenia in children. That disorder is often associated with autoantibodies against erythroid progenitors.³⁰ Transient erythroblastopenia in children may be associated with viral infection. It is possible that the transient appearance of an antierythropoietin antibody in our patient was related to such a mechanism.

Supported by a contract with the Association pour la Recherche sur le Cancer (6327) and a grant from the Ligue Nationale contre le Cancer (Comité de Paris).

We are indebted to Dr. Samuel A. Burstein for assistance in the preparation of the manuscript.

Source Information

From the Department of Hematology, Hôpital R. Poincaré, Garches (N.C.); the Department of Hematology, Hôpital Lariboisière, Paris (E.D., P.M.-S., G.T.); the Department of Hematology, Hôpital Necker, Paris (B.V.); INSERM Unité 362, Villejuif (N.C.); and Institut Cochin de Génétique Moléculaire, INSERM Unité 363, Paris (P.M.) — all in France.

Address reprint requests to Dr. Casadevall at the Department of Hematology, Hôpital R. Poincaré, 104 Blvd. Raymond Poincaré, 92 380 Garches, France.

References

1. Dessypris EN. The biology of pure red cell aplasia. Semin Hematol 1991;28:275-284. [Medline]
2. Krantz SB. Pure red-cell aplasia. N Engl J Med 1974;291:345-350.
3. DiGiacomo J, Furst SW, Nixon DD. Primary acquired red cell aplasia in the adult. J Mt Sinai Hosp N Y 1966;33:382-395. [Medline]
4. Krantz SB, Kao V. Studies on red cell aplasia. II. Report of a second patient with an antibody to erythroblast nuclei and a remission after immunosuppressive therapy. Blood 1969;34:1-13. [Free Full Text]
5. Francis DA. Pure red-cell aplasia: association with systemic lupus erythematosus and primary autoimmune hypothyroidism. BMJ 1982;284:85-88. 
6. Barnes RD. Refractory anaemia with thymoma. Lancet 1966;2:1464-1464. 
7. Krantz SB, Kao V. Studies on red cell aplasia. I. Demonstration of a plasma inhibitor to heme synthesis and an antibody to erythroblast nuclei. Proc Natl Acad Sci U S A 1967;58:493-500. [Free Full Text]
8. Eisemann G, Dameshek W. Splenectomy for "pure red-cell" hypoplastic (aregenerative) anemia associated with autoimmune hemolytic disease. N Engl J Med 1954;251:1044-1048. [Medline]
9. Lacombe C, Casadevall N, Muller O, Varet B. Erythroid progenitors in adult chronic pure red cell aplasia: relationship of in vitro erythroid colonies to therapeutic response. Blood 1984;64:71-77. [Free Full Text]
10. Marmont A, Peschle C, Sanguineti M, Condorelli M. Pure red cell aplasia (PRCA): response of three patients to cyclophosphamide and/or antilymphocyte globulin (ALG) and demonstration of two types of serum IgG inhibitors to erythropoiesis. Blood 1975;45:247-261. [Free Full Text]
11. Krantz SB. Studies on red cell aplasia. 3. Treatment with horse antihuman thymocyte gamma globulin. Blood 1972;39:347-360. [Free Full Text]
12. Zaentz SD, Krantz SB, Brown EB. Studies on pure red cell aplasia: maintenance therapy with immunosuppressive drugs. Br J Haematol 1976;32:47-54. [Medline]
13. Khelif A, Van HV, Tremisi JP, et al. Remission of acquired pure red cell aplasia following plasma exchanges. Scand J Haematol 1985;34:13-15. [Medline]
14. Messner HA, Fauser AA, Curtis JE, Dotten D. Control of antibody-mediated pure red-cell aplasia by plasmapheresis. N Engl J Med 1981;304:1334-1338. [Medline]
15. Krantz SB, Moore WH, Zaentz SD. Studies on red cell aplasia. V. Presence of erythroblast cytotoxicity in G-globulin fraction of plasma. J Clin Invest 1973;52:324-336.
16. Zaentz SD, Krantz SB. Studies on pure red cell aplasia. VI. Development of two-stage erythroblast cytotoxicity method and role of complement. J Lab Clin Med 1973;82:31-43. [Medline]
17. Maung ZT, Norden J, Middleton PG, Jack FR, Chandler JE. Pure red cell aplasia: further evidence of T cell clonal disorder. Br J Haematol 1994;87:189-192. [Medline]
18. Mangan KF, Volkin R, Winkelstein A. Autoreactive erythroid progenitor-T suppressor cells in the pure red cell aplasia associated with thymoma and panhypogammaglobulinemia. Am J Hematol 1986;23:167-173. [Medline]
19. Hoffman R, Kopel S, Hsu SD, Dainiak N, Zanjani ED. T cell chronic lymphocytic leukemia: presence in bone marrow and peripheral blood of cells that suppress erythropoiesis in vitro. Blood 1978;52:255-260. [Free Full Text]
20. Nagasawa T, Abe T, Nakagawa T. Pure red cell aplasia and hypogammaglobulinemia associated with Tr-cell chronic lymphocytic leukemia. Blood 1981;57:1025-1031. [Free Full Text]
21. Mangan KF, D'Alessandro L. Hypoplastic anemia in B cell chronic lymphocytic leukemia: evolution of T cell-mediated suppression of erythropoiesis in early-stage and late-stage disease. Blood 1985;66:533-541. [Free Full Text]
22. Jepson JH, Lowenstein L. Panhypoplasia of the bone marrow. I. Demonstration of a plasma factor with anti-erythropoietin-like activity. Can Med Assoc J 1968;99:99-101. [Medline]
23. Peschle C, Marmont AM, Marone G, Genovese A, Sasso GF, Condorelli M. Pure red cell aplasia: studies on an IgG serum inhibitor neutralizing erythropoietin. Br J Haematol 1975;30:411-417. [Medline]
24. McLeod DL, Shreeve MM, Axelrad AA. Improved plasma culture system for production of erythrocytic colonies in vitro: quantitative assay method for CFU-E. Blood 1974;44:517-534. [Free Full Text]
25. Mayeux P, Casadevall N, Lacombe C, Muller O, Tambourin P. Solubilization and hydrodynamic characteristics of the erythropoietin receptor: evidence for a multimeric complex. Eur J Biochem 1990;194:271-278. [Medline]
26. Mayeux P, Casadevall N, Muller O, Lacombe C. Glycosylation of the murine erythropoietin receptor. FEBS Lett 1990;269:167-170. [CrossRef][Medline]
27. Dordal MS, Wang FF, Goldwasser E. The role of carbohydrate in erythropoietin action. Endocrinology 1985;116:2293-2299. [Abstract]
28. Komatsu N, Nakauchi H, Miwa A, et al. Establishment and characterization of a human leukemic cell line with megakaryocytic features: dependency on granulocyte-macrophage colony-stimulating factor, interleukin-3, or erythropoietin for growth and survival. Cancer Res 1991;51:341-348. [Free Full Text]
29. Hermine O, Mayeux P, Titeux M, et al. Granulocyte-macrophage colony-stimulating factor and erythropoietin act competitively to induce two different programs of differentiation in the human pluripotent cell line UT-7. Blood 1992;80:3060-3069. [Free Full Text]
30. Dessypris EN, Krantz SB, Roloff JS, Lukens JN. Mode of action of the IgG inhibitor of erythropoiesis in transient erythroblastopenia of children. Blood 1982;59:114-123. [Free Full Text]

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• Murakawa, T., Nakajima, J., Sato, H., Tanaka, M., Takamoto, S., Fukayama, M. (2002). Thymoma Associated With Pure Red-Cell Aplasia: Clinical Features and Prognosis. Asian Cardiovasc. Thorac. Ann. 10: 150-154 [Abstract] [Full Text]  
• Mercadal, L., Sutton, L., Casadevall, N., Bagnis, C., Jacobs, C. (2002). Immunological reaction against erythropoietin causing red-cell aplasia. Nephrol Dial Transplant 17: 943-943 [Full Text]  
• Casadevall, N., Nataf, J., Viron, B., Kolta, A., Kiladjian, J.-J., Martin-Dupont, P., Michaud, P., Papo, T., Ugo, V., Teyssandier, I., Varet, B., Mayeux, P. (2002). Pure Red-Cell Aplasia and Antierythropoietin Antibodies in Patients Treated with Recombinant Erythropoietin. NEJM 346: 469-475 [Abstract] [Full Text]  
• Li, J., Yang, C., Xia, Y., Bertino, A., Glaspy, J., Roberts, M., Kuter, D. J. (2001). Thrombocytopenia caused by the development of antibodies to thrombopoietin. Blood 98: 3241-3248 [Abstract] [Full Text]  
• Silvestris, F., Tucci, M., Cafforio, P., Dammacco, F. (2001). Fas-L up-regulation by highly malignant myeloma plasma cells: role in the pathogenesis of anemia and disease progression. Blood 97: 1155-1164 [Abstract] [Full Text]  
• Kuwaki, T., Hagiwara, T., Kato, T., Miyazaki, H. (2000). Autoantibodies neutralizing thrombopoietin in a patient with a megakaryocytic thrombocytopenic purpura. Blood 95: 2187-2188 [Full Text]  
• Voulgarelis, M., Kokori, S. I G, Ioannidis, J. P A, Tzioufas, A. G, Kyriaki, D., Moutsopoulos, H. M (2000). Anaemia in systemic lupus erythematosus: aetiological profile and the role of erythropoietin. Ann Rheum Dis 59: 217-222 [Abstract] [Full Text]  
• Handgretinger, R., Geiselhart, A., Moris, A., Grau, R., Teuffel, O., Bethge, W., Kanz, L., Fisch, P. (1999). Pure Red-Cell Aplasia Associated with Clonal Expansion of Granular Lymphocytes Expressing Killer-Cell Inhibitory Receptors. NEJM 340: 278-284 [Full Text]  
• Abina, M.-A., Tulliez, M., Duffour, M.-T., Debili, N., Lacout, C., Villeval, J.-L., Wendling, F., Vainchenker, W., Haddada, H. (1998). Thrombopoietin (TPO) Knockout Phenotype Induced by Cross-Reactive Antibodies Against TPO Following Injection of Mice with Recombinant Adenovirus Encoding Human TPO. J. Immunol. 160: 4481-4489 [Abstract] [Full Text]  
• Tassignon, J., Haeseleer Abraham Borkowski, F. (1997). Natural Antiestrogen Receptor Autoantibodies in Man with Estrogenic Activity in Mammary Carcinoma Cell Culture: Study of their Mechanism of Action; Evidence for Involvement of Estrogen-Like Epitopes. J. Clin. Endocrinol. Metab. 82: 3464-3470 [Abstract] [Full Text]  
• Urra, J. M., Miguel de la Torre, , Alcazar, R., Peces, R. (1997). Rapid Method for Detection of Anti-Recombinant Human Erythropoietin Antibodies as a New Form of Erythropoietin Resistance. Clin. Chem. 43: 848-849 [Full Text]  
• Palmieri, G., Lastoria, S., Colao, A., Vergara, E., Varrella, P., Biondi, E., Selleri, C., Catalano, L., Lombardi, G., Bianco, A. R., Salvatore, M. (1997). Successful Treatment of a Patient with a Thymoma and Pure Red-Cell Aplasia with Octreotide and Prednisone. NEJM 336: 263-265 [Full Text]  
• Peces, R., de la Torre, M., Alcazar, R., Urra, J. M. (1996). Antibodies against Recombinant Human Erythropoietin in a Patient with Erythropoietin-Resistant Anemia. NEJM 335: 523-524 [Full Text]  
• Lacombe, C. (1996). Resistance to Erythropoietin. NEJM 334: 660-662 [Full Text]