Pure red cell aplasia

Introduction

Introduction to pure red blood cell aplasia

Pure-cellanemia (PRCA) refers to an anemia caused by a significant decrease or deficiency of erythroid cells in the bone marrow.

basic knowledge

The proportion of illness: 0.035%

Susceptible people: no specific people

Mode of infection: non-infectious

Complications: anemia

Pathogen

Causes of pure red blood cell aplasia

(1) Causes of the disease

1. Thymoma: About 50% of patients with thymoma, mostly benign.

2. Infection: such as infectious mononucleosis, mumps, respiratory infections, viral hepatitis, mycoplasmal pneumonia, etc.

3. Autoimmune diseases: such as systemic lupus erythematosus, rheumatoid arthritis, etc., adult Stii disease, hyperthyroidism.

4. Neoplastic diseases: such as malignant lymphoma, chronic lymphocytic leukemia, chronic myeloid leukemia, vascular immunoblastic lymphadenopathy, cholangiocarcinoma, thyroid cancer, breast cancer, bronchial lung cancer, etc.

5. Drug factors: Certain drugs such as chloramphenicol, isoniazid, sulphur sputum, phenytoin, acetaminophen (paracetamol) can induce PRCA, most of which are acute processes, and most cases can be completely recovered.

(two) pathogenesis

Most of the pathogenesis is related to immune factors. The pathogenesis is currently considered: 1 humoral immune abnormalities: some patients have plasma IgG selective inhibitory activity against erythroid cells; 2 cellular immune abnormalities: some patients have decreased or inverted CD4+/CD8+ ratio, and there are T lymphocytes Cell-mediated immune damage of erythroid cells; 3 some drugs have direct toxic effects on erythroid progenitor cells; 4 virus induced, such as B19 parvovirus infection can induce apoptosis of erythroid progenitor cells.

1. Immune-mediated PRCA

(1) Humoral immune-mediated PRCA: Early studies have shown that injection of PRCA patients into the experimental animals can inhibit bone marrow erythroid hematopoiesis. Further studies have shown that the plasma inhibitory activity of PRCA patients is derived from their IgG components (PRCA-IgG). PRCA-IgG showed inhibition of growth of autologous and normal erythroid progenitor cells (BFU-E and CFU-E) in a concentration-dependent manner, but did not grow on self and normal granulocyte-monoblast progenitor cells (CFU-GM). Significantly, the concentration of PRCA-IgG in patients with remission decreased or disappeared. The exact mechanism of PRCA-IgG hematopoietic inhibition activity is not known. It is known that PRCA-IgG does not interfere with residual BFU-E and CFU-E on erythropoietin (EPO). In addition, PRCA-IgG lacks direct cytotoxicity to 59Fe-labeled self and normal BFU-E and CFU-E, and only a few patients with PRCA-IgG can directly damage their own CFU-E. Complement-dependent and non-complement-dependent, anti-EPO antibodies exist in individual patients. Anti-EPO receptor (EPOR) antibodies have not been found in PRCA patients. BFU-E, CFU-E and morphologically identifiable in PRCA patients Erythroid cells are severely uneven The decrease in sex, therefore, the PRCA-IgG inhibitory activity is highly variable, and may act on cells of different developmental stages of erythroid hematopoiesis, and in most cases, complement is required to participate. Currently, the target antigen for PRCA-IgG inhibitory activity is not clear, and it is speculated that For EPOR.

(2) T lymphocyte-mediated PRCA: based on a considerable proportion of patients lacking PRCA-IgG inhibitory activity, combined with PRCA and thymoma and chronic lymphocytic leukemia (CLL), and clinical thymectomy and anti-T lymph The effectiveness of immunosuppressive agents in the treatment of PRCA, many scholars believe that the main pathological mechanism of PRCA is T lymphocyte-mediated BFU-E and CFU-E immune damage, the number of T and NK cells in the above patients is significantly increased, remove T or NK The number of BFU-E and CFU-E in the bone marrow of the cells increased progressively and returned to normal levels. T cells in vitro showed significant inhibitory effects on normal and self-BFU-E and CFU-E.

2. Drug-related PRCA It is known that a variety of drugs may be associated with PRCA, especially isoniazid, chloramphenicol, azathioprine and methyldopa are the most common, some scholars from a case of diphenyl caprolactam A unique PRCA-IgG isolated from patients with PRCA induced by diphenylhydantion, which can significantly delay the growth of BFU-E and CFU-E in vitro only with the participation of diphenylhydantoin, due to the majority of drug-related PRCA patients. There is no similar abnormal immune response, so the main pathological mechanism is generally considered to be the direct toxic effect of related drugs on BFU-E and CFU-E.

3. Virus-induced PRCA It is now clear that the vast majority of transient PRCA is caused by B19 parvovirus infection. B19 parvovirus is a DNA virus with specific tropism and height for BFU-E and CFU-E. Affinity, its receptor is globoside, ubiquitous proliferation of B19 parvovirus after invading BFU-E, its non-structural protein can directly induce BFU-E and CFU-E to "apoptosis"-like extinction. The technique found that B19 parvovirus DNA was present in the serum of 8/57 patients with PRCA, immunodeficiency (such as AIDS patients) and patients with immunosuppressive therapy were concurrent with persistent B19 parvovirus infection, resulting in chronic refractory PRCA.

Prevention

Pure red blood cell aplastic disorder prevention

1. Patients with thymoma can be removed early.

2. Enhance physical fitness and prevent infection.

3. Avoid or reduce the use of chloramphenicol, sulphur sputum, acetaminophen and other drugs.

Complication

Pure red blood cell aplasia complications Complications anemia

Anemia can be complicated by anemia.

Symptom

Pure red blood cell aplastic symptoms common symptoms dizziness, fatigue, shortness of breath, shortness of breath

Anemia is the main symptoms and signs of patients with this disease, slow onset, may have dizziness, fatigue, palpitations, shortness of breath, generally no bleeding and fever, no lymphadenopathy, hepatosplenomegaly.

1. Anemia is the main clinical manifestation, no bleeding, fever, physical examination and hepatosplenomegaly.

2. Peripheral blood showed positive cell anemia, reticulocyte absolute value decreased, white blood cell and platelet count were normal, and the total number and classification of blood cells were normal.

3. The cells of the bone marrow erythroid system were significantly reduced or even absent, and the granulocyte megakaryocyte cell line was normal.

It can be diagnosed according to the above three characteristics. The conditional cells are cultured in vitro, and the erythrocyte colony forming unit (CFU-E) does not grow.

Examine

Pure red cell aplasia check

1. Blood routine: Hemoglobin, red blood cell reduction, reticulocyte significantly reduced, positive cell anemia, white blood cell and platelet count in the normal range, white blood cell classification is normal, red blood cells and platelet morphology are normal, no pathological hematopoiesis.

2. MCV, MCH and MCHC are normal.

3. Bone marrow: The red system is significantly reduced, the granulocyte and megakaryocyte system are normal at various stages, and there are not many granules and early granules. In some patients, megakaryocytes increase and fat cells do not increase.

4. Ham and Coombs test negative, serum iron, total iron binding capacity and ferritin increased.

Imaging examination, chest X-ray examination can be found in thymoma, CT and nuclear resonance examination if necessary, such as chromosome examination when identifying with MDS.

Diagnosis

Diagnosis and diagnosis of pure red blood cell aplastic

1. Congenital constitutional PRCA, infants and young children, easy to combine various congenital malformations.

2. Myelodysplastic syndrome (MDS) Among them, refractory anemia (MDS-RA) is easily confused with pure red aplasticity. MDS-RA bone marrow cells can be seen morbid hematopoiesis, and chromosome examination abnormality accounts for 20%. ~60%, bone marrow tissue sections showed abnormal distribution of pre-hematopoietic cells, and immunosuppressive therapy was ineffective.

3. Paroxysmal nocturnal hemoglobinuria (PNH), especially hemoglobinuria is not easy to be confused with pure red aplastic anemia, the reticulocyte often increases in the disease, bone marrow erythrocytes proliferate urine hemosiderin, expand the test and Ham The test was positive and both contributed to the identification.