Clinical Implication of Serum Anti-p53 Antibodies and Overexpression of p53 Protein in Myelodysplastic Syndrome and Acute Myeloid Leukemia / 대한혈액학회지

BACKGROUND: Alteration of p53 genes is rare, but it is related with progressive diseases in hematologic malignancies. The wild type of p53 protein is not usually detected, but mutated p53 proteins are accumulated in the nuclei of tumor cells, which can be detected by immunohistochemical stain. Anti-p53 antibodies are found in the sera of patients with various malignant tumors as the result of immune response to accumulation of mutated p53 protein in tumor cells. METHODS: The relation of serum anti-p53 anti-bodies and cellular p53 protein expression to clinical features in 36 cases of myelodysplastic syndrome (MDS) and 58 cases of acute myeloid leukemia (AML) was analyzed. Anti-p53 antibodies in the patient's sera were measured with enzyme immunoassay (p53 autoantibodies ELISA, Dianova, Hamburg, Germany). Immunohistochemical staining for p53 protein was performed with the streptavidin-biotin-peroxidase method (LSAB kit, DAKO, Denmark) and anti-p53 monoclonal antibody (DO-7, DAKO, Denmark) in paraffin embedded bone marrow biopsy sections. RESULTS: Anti-p53 antibodies were positive in one of 36 (2.7%) MDS cases, and in four of 58 (6.8%) AML cases. Overexpression of p53 protein was seen in five (13.9%) of MDS and in five (8.6%) of AML. Serum p53 antibodies and p53 protein overexpression were more frequently found in RAEB, RAEB-t and M6 sutypes. There was no relation between anti-p53 antibodies and p53 protein overexpression in MDS and AML. The patients of MDS with anti-p53 antibodies and p53 overexpression tended to have severe dyserythropoiesis, higher Bounemouth scores and poor prognostic karyotypes and associated with shorter survival duration as compared to those without anti-p53 antibodies and p53 overexpression (4+/-1 vs 26+/-4 months, P=0.007). The patients of AML with anti-p53 antibodies and p53 protein overexpression tended to have poor prognostic karyotypes and resistance to chemotherapy. CONCLUSION: Anti-p53 antibodies are rarely observed in sera of patients with MDS and AML, probably reflecting the relatively low incidence of p53 mutation. But the findings suggest that the presence of p53 alteration could be useful to predict resistance to chemotherapy and short survival in particular sutypes of MDS and AML.

Clinical Significance of p53 Protein Overexpression and Serum Anti-p53 Antibodies in Patients with Acute and Chronic Leukemia / 대한임상병리학회지

BACKGROUND: Mutations of p53 gene, rarely found in leukemia, result in accumulation of mutated p53 protein in the nuclei of tumor cells, which can be detected by immunohistochemistry. Lately, anti-p53 antibodies were found in the sera of patients who had solid tumors as a result of immune response to accumulation of mutated p53 protein in tumor cells. METHODS: For investigation of the clinical implication of cellular p53 protein overexpression and serum p53 antibody, immunohistochemical staining for p53 protein of B-5 fixed paraffin embedded bone marrow biopsies and enzyme immunoassay for the presence of anti-p53 antibodies of sera were performed simultanously; in 58 cases of AML, 34 cases of ALL, 11 cases of acute leukemia at relapse, 13 cases of CML in chronic phase and 5 cases of CLL. RESULTS: Overexpression of p53 protein was found in 9.1%(11/121) of all leukemias, with 8.6% of AML with predominance of M6, 5.9% of ALL, 18.2% of acute leukemia at relapse and 40% of CLL, but not found in CML. Serum anti-p53 antibodies were found in 5.8%(7/121) of all leukemias, with 6.9% of AML and 5.9% of ALL, 9.1% of acute leukemia at relapse, but not found in chronic leukemias. In AML and ALL, age, sex, hemoglobin, leukocyte count, platelet count and blast % were not related with p53 protein expression. The AML patients with p53 protein overexpression have more unfavorable karyotypes(complex karyotype, -5, -7 and t(10;11)), with shorter overall survival as compared to those without p53 protein overexpression. The presence of serum anti-p53 antibodies was not related with clinical findings of leukemias. CONCLUSIONS: The indications are that p53 gene alterations will contribute to disease development and progression in some specific patients with leukemia, due to the rare frequency of overexpression of p53 protein and serum anti-p53 antibodies in leukemia. Analysis of the p53 protein and serum p53 antibodies could screen p53 gene mutation and predict prognosis for some leukemias.

Clinical Usefulness of Measurement of Reticulated Platelets by Thiazole Orange in Idiopathic Thrombocytopenic Purpura / 대한임상병리학회지

BACKGROUND: Reticulated platelets (RP) are young platelets with a high mRNA that are newly produced from the bone marrow. Thiazole orange (TO) has been a RNA staining fluorescent dye for reticulocyte, and used for RP recently. The increased percentage of RP (RP%) reflects immaturity and hematopoietic activity of platelets, therefore it may be useful for the diagnosis of idiopathic thrombocytopenic purpura (ITP). METHODS: To assess the usefulness of RP in diagnosing ITP, we compared with RP%s of 50 ITP patients, 35 thrombocytopenic patients due to impaired production and 87 heathly normal controls. Platelets were stained with TO dye, followed by flowcytometric analysis. Platelet associated IgG (PAIgG) was also measured with the same samples. The standard gate was used as a reference with the unstained sample from a normal subject and the RP% was expressed as the percentage of TO positive cells of platelets. RESULTS: The RP% of patients with ITP was significantly higher than those of thrombocytopenia due to impaired platelet production and healthy controls (24.4+/-14.3% vs 8.6+/-5.2% and 8.0+/-5.1%, respectively). There was negative correlation between the platelet count and RP%, and positive correlation between MPV and RP%. In diagnosing for ITP, the sensistivity and specificity of RP% were 81% and 92%, respectively, and more valuable than those of PAIgG test. Using RP% and PAIgG at the same time, the diagnostic efficiency for ITP was not improved. The RP% of an ITP patient was changed to correspond with the disease progression, and that of an AML patient following chemotherapy was increased to precede the rising of the platelet count. CONCLUSION: It suggest that the measurement of reticulated platelets is a very useful test for diagnosis of ITP, furthermore it can be used to estimate the thrombopoietic activity before bone marrow examination.