Prostate-specific antigen in serum occurs predominantly in complex with alpha 1-antichymotrypsin

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Immunologic measurements of the serum concentration of prostate-specific antigen (PSA), an abundant prostatic-secreted serine proteinase, are frequently used to monitor patients with prostate cancer, though it has not been ascertained whether this immunoreactivity represents a PSA zymogen, the active proteinase, or PSA complexed to extracellular proteinase inhibitors. To characterize the PSA immunoreactivity in serum, we used monoclonal antibodies produced against PSA and a polyclonal rabbit IgG against alpha 1-antichymotrypsin in the design of three noncompetitive PSA assays: assay T, which detected PSA both when present as the active proteinase and when complexed to alpha 1-antichymotrypsin; assay F, which recognized the active proteinase but most poorly detected PSA complexed to alpha 1-antichymotrypsin; and assay C, which was specific for PSA complexed to alpha 1-antichymotrypsin. We used the three assays to measure PSA immunoreactivity in 64 patients' sera and in the effluent after gel chromatography of sera from four patients. This identified an 80- to 90-kDa complex between PSA and alpha 1-antichymotrypsin as the predominant fraction of the PSA immunoreactivity in blood plasma; an immunoreactive 25- to 40-kDa compound was the minor fraction.


  • H Lilja
  • A Christensson
  • U Dahlén
  • M T Matikainen
  • O Nilsson
  • K Pettersson
  • T Lövgren
Externa organisationer
  • Skåne University Hospital

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Läkemedelskemi


Sidor (från-till)1618-25
Antal sidor8
TidskriftClinical Chemistry
Utgåva nummer9
StatusPublished - 1991 sep
Peer review utfördJa
Externt publiceradJa