title: Characterization of Monoclonal Antibodies against Human Leukocyte Common Antigen (CD45).
abstract: BACKGROUND
  The leukocyte common antigen (CD45) is a transmembrane-type protein tyrosine phosphatase that has five isoforms.
  
  
  METHODS
  We generated seven murine mAbs against human CD45 by injecting cells from different origins, such as human thymocytes, PBMCs, and leukemic cell lines. By using various immunological methods including flow cytometry, immunohistochemistry, and immunoprecipitation, we evaluated the reactivity of those mAbs to CD45 of thymus as well as tonsil lysates. Furthermore, we transiently transfected COS-7 cells with each of gene constructs that express five human CD45 isoforms respectively, and examined the specificities of the mAbs against the transfected isoforms.
  
  
  RESULTS
  In case of thymocytes, lymphocytes, and monocytes, all the seven mAbs demonstrated positive reactivities whereas none was reactive to erythrocytes and platelets. The majority of immune cells in formalin-fixed paraffin-embedded thymus and tonsil tissues displayed strong membranous immunoreactivity, and the main antigen was detected near 220 kDa in all cases. Among the mAbs, four mAbs (AP4, DN11, SHL-1, and P6) recognized a region commonly present in all the five isoforms. One mAb, YG27, recognized four isoforms (ABC, AB, BC, and O). Two mAbs, P1 and P14, recognized the isoforms that contain exon A encoded regions (ABC and AB).
  
  
  CONCLUSIONS
  In this study, we confirmed that AP4, DN11, SHL-1, YG27 and P6, are mAbs reactive with the CD45 antigen whereas P1 and P14 are reactive with the CD45RA antigen.
authors.affiliation: Department of Pathology, Chungbuk National University College of Medicine, Cheongju 361-763, Korea.
authors.forename: Hyang-Mi
authors.initials: HM
authors.lastname: Shin
authors.forename: Woon-Dong
authors.initials: WD
authors.lastname: Cho
authors.forename: Geon-Kook
authors.initials: GK
authors.lastname: Lee
authors.forename: Seon-Hwa
authors.initials: SH
authors.lastname: Lee
authors.forename: Kyung-Mee
authors.initials: KM
authors.lastname: Lee
authors.forename: Gil-Yong
authors.initials: GY
authors.lastname: Ji
authors.forename: Sang-Soon
authors.initials: SS
authors.lastname: Yoon
authors.forename: Ji-Hae
authors.initials: JH
authors.lastname: Koo
authors.forename: Ho-Chang
authors.initials: HC
authors.lastname: Lee
authors.forename: Ki-Hyeong
authors.initials: KH
authors.lastname: Lee
authors.forename: Hyung-Geun
authors.initials: HG
authors.lastname: Song