title: Characterization of monoclonal antibodies against prostate specific antigen produced by genetic immunization.
abstract: Prostate specific antigen (PSA) is the most important marker for prostate cancer. Antibodies against minor variants of PSA may be useful in the development of novel diagnostic tests for prostate cancer, but it has been difficult to produce such antibodies by protein immunization. In this study, we have compared the characteristics of monoclonal antibodies (MAbs) obtained by genetic immunization with those obtained by protein immunization. The whole coding region of PSA-cDNA was cloned in a mammalian expression vector pCDNA-3. Six mice were immunized four times by intra-muscular (i.m.) injection of the PSA-pCDNA3 plasmid. The MAbs produced were characterized with respect to subclass, epitope specificity, binding to various molecular forms of PSA and affinity. After intra-muscular injection of DNA, anti-PSA antibodies were detected in the serum of all mice, but the antibody titers were markedly lower than after protein immunization. After fusion of the spleen cells from the mice, five hybridomas producing MAbs to PSA were obtained. The MAbs were of IgG1 and IgG2a isotype and they all recognized equally different forms of free PSA, namely enzymatically active, nicked and proPSA. Epitope mapping showed that these MAbs reacted with the same antigenic regions as those obtained by protein immunization. Thus, genetic immunization leads to production of anti PSA MAbs with similar characteristics to those obtained by immunizing with PSA protein. As applied in the present study, it is less efficient than protein immunization, but it is a useful technique when the antigen is not available in the quantities needed for immunization.
authors.affiliation: Department of Clinical Chemistry in Biomedicum, Helsinki University Central Hospital, Finland. jari.leinonen@hus.fi
authors.forename: Jari
authors.initials: J
authors.lastname: Leinonen
authors.forename: Pauliina
authors.initials: P
authors.lastname: Niemelä
authors.forename: Janita
authors.initials: J
authors.lastname: Lövgren
authors.forename: Letizia
authors.initials: L
authors.lastname: Bocchi
authors.forename: Kim
authors.initials: K
authors.lastname: Pettersson
authors.forename: Heli
authors.initials: H
authors.lastname: Nevanlinna
authors.forename: Ulf-Håkan
authors.initials: UH
authors.lastname: Stenman
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000008:administration & dosage / Q000276:immunology; D018604:Epitope Mapping; D005822:Genetic Vectors / Q000235:genetics; D006825:Hybridomas / Q000378:metabolism; D007114:Immunization / Q000379:methods*; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology; D007273:Injections, Intramuscular; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D017430:Prostate-Specific Antigen / Q000235:genetics* / Q000276:immunology*; D011487:Protein Conformation
chemical_list: D000911:Antibodies, Monoclonal; D018076:DNA, Complementary; D007074:Immunoglobulin G; D017430:Prostate-Specific Antigen