title: Significance of CD99 expression in T-lineage acute lymphoblastic leukemia.
abstract: BACKGROUND
  CD99 was first isolated as an antigen on the T acute lymphoblastic leukemia cells. It has been shown to participate in T cell adhesion and is widely expressed on a variety of hematopoietic and non-hematopoietic cell types.
  
  
  OBJECTIVE
  Detection of the expression pattern of CD99 on leukemic and normal T cells and assessing the possibility of its use as a tool for the diagnosis and monitoring of T-ALL cases.
  
  
  METHODS
  We used flow cytometry technique to determine the expression level of CD99 in 62 newly diagnosed T-ALL patients. Patients were followed up for the presence of minimal residual disease on day 15 and day 42 post-therapy. 20 age and sex matched healthy controls were enrolled in our study.
  
  
  RESULTS
  CD99 was expressed in all T-ALL patients, with a higher median expression level when compared to controls (58.5% versus 1.38%, p< 0.001). On day 42 post-therapy, 100% of follow up patients who had initial CD99 expression ≤ 50% had no minimal residual disease, while only 45.5% of those who had initial CD99 expression > 50% had no minimal residual disease (P= 0.03). There was no significant influence of CD99 expression on the 1-year overall survival probability (P= 0.82).
  
  
  CONCLUSIONS
  CD99 could be used to complement current strategy relying on TdT for diagnosis and monitoring of minimal residual disease during the post-therapy follow up of T-ALL patients. Further studies are needed to confirm these findings.
authors.affiliation: Clinical and Chemical Pathology Department, Kasr Al Aini, Faculty of Medicine, Cairo University, Cairo, Egypt.
authors.forename: Azza A Aboul
authors.initials: AA
authors.lastname: Enein
authors.affiliation: Clinical and Chemical Pathology Department, Kasr Al Aini, Faculty of Medicine, Cairo University, Cairo, Egypt.
authors.forename: Hala A Abdel
authors.initials: HA
authors.lastname: Rahman
authors.affiliation: Clinical Pathology Department, National Cancer Institute, Cairo University, Cairo, Egypt.
authors.forename: Nahla El
authors.initials: NE
authors.lastname: Sharkawy
authors.affiliation: Clinical and Chemical Pathology Department, Kasr Al Aini, Faculty of Medicine, Cairo University, Cairo, Egypt.
authors.forename: Samah Abd
authors.initials: SA
authors.lastname: Elhamid
authors.affiliation: Pediatric Oncology Department, National Cancer Institute, Cairo University, Cairo, Egypt.
authors.forename: Sonia M A
authors.initials: SM
authors.lastname: Abbas
authors.affiliation: Department of Medical Oncology, National Cancer Institute, Cairo University, Cairo, Egypt.
authors.forename: Rafaat
authors.initials: R
authors.lastname: Abdelfaatah
authors.affiliation: Clinical Pathology Department, National Cancer Institute, Cairo University, Cairo, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Khalil
authors.affiliation: Clinical Pathology Department, National Cancer Institute, Cairo University, Cairo, Egypt.
authors.forename: Lamiaa A
authors.initials: LA
authors.lastname: Fathalla
mesh_terms: D000071443:12E7 Antigen / Q000235:genetics / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000378:metabolism; D015415:Biomarkers; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D016130:Immunophenotyping; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis / Q000378:metabolism* / Q000401:mortality / Q000628:therapy; D012372:ROC Curve; D012074:Remission Induction; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; D015415:Biomarkers
keywords: CD99; T acute lymphoblastic leukemia; disease free survival