PMID- 10102908
OWN - NLM
STAT- MEDLINE
DCOM- 19990414
LR  - 20190722
IS  - 0009-9147 (Print)
IS  - 0009-9147 (Linking)
VI  - 45
IP  - 4
DP  - 1999 Apr
TI  - Epitope analysis of a prostate-specific antigen (PSA) C-terminal-specific 
      monoclonal antibody and new aspects for the discrepancy between equimolar and 
      skewed PSA assays.
PG  - 486-96
AB  - BACKGROUND: Immunoassays to measure prostate-specific antigen (PSA) often give 
      different values for the same patient samples, and the calibrators among 
      commercial immunoassays are not interchangeable. We developed three novel assays 
      to quantify the free and complexed forms of PSA in serum. METHODS: We synthesized 
      46 peptides, which encompassed the entire PSA molecule, and determined the 
      interactions between selected monoclonal antibodies (MAbs) and those peptides or 
      the intact PSA molecule. RESULTS: MAb PA313 did not cross-react with human 
      glandular kallikrein (hK2), which has 78% amino acid homology to PSA. This MAb 
      bound with KD = 40 nmol/L to the C-terminal peptide of PSA and distinguished 
      between a synthetic peptide derived from PSA (PSA46A: 
      NH2-C-R226KWIKDTIVANP237-COOH) that differed from one derived from hK2 (PSA46B: 
      NH2-C-R226KWIKDTAANP237-COOH) by a single amino acid. Only the MAb combination of 
      PA313/PA121 showed equimolar reactivity with PSA and with PSA complexed with 
      alpha1-antichymotrypsin (PSA-ACT). The free form of PSA (F-PSA) was determined by 
      MAbs PA313/FPA503, and the amount of complexed PSA (C-PSA) in PSA-ACT was 
      determined by alphaACT/PA313. The total PSA (T-PSA) measured by either of the 
      equimolar assays (PA313/PA121 or Tandem-R) was consistent with the sum of F-PSA 
      and C-PSA. In contrast, T-PSA by a skewed assay (IMx) was higher than F-PSA + 
      C-PSA when the ratio of F-PSA to T-PSA (F/T) was >0.15. T-PSA measured by IMx was 
      nearly equal to F-PSA/0.55 + C-PSA. The coefficient 0.55 reflected different 
      reactivities of the IMx assay with PSA-ACT and PSA. CONCLUSION: The discrepancy 
      between the values measured by equimolar and skewed assays depends on the ratio 
      of free to total PSA in the sample.
CI  - Copyright 1999 American Association for Clinical Chemistry
FAU - Nagasaki, H
AU  - Nagasaki H
AD  - Department of Medical Science, Cosmo Research Institute for Biomedical Research, 
      1134-2 Gongendo, Satte, Saitama 340-0193, Japan. hiroshi_nagasaki@cosmo-oil.co.jp
FAU - Watanabe, M
AU  - Watanabe M
FAU - Komatsu, N
AU  - Komatsu N
FAU - Kaneko, T
AU  - Kaneko T
FAU - Dube, J Y
AU  - Dube JY
FAU - Kajita, T
AU  - Kajita T
FAU - Saitoh, Y
AU  - Saitoh Y
FAU - Ohta, Y
AU  - Ohta Y
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PL  - England
TA  - Clin Chem
JT  - Clinical chemistry
JID - 9421549
RN  - 0 (Antibodies, Monoclonal)
RN  - 0 (Epitopes)
RN  - 0 (Peptide Fragments)
RN  - EC 3.4.21.- (Kallikreins)
RN  - EC 3.4.21.1 (Chymotrypsin)
RN  - EC 3.4.21.35 (Tissue Kallikreins)
RN  - EC 3.4.21.77 (Prostate-Specific Antigen)
SB  - IM
MH  - Amino Acid Sequence
MH  - *Antibodies, Monoclonal
MH  - Antibody Specificity
MH  - Blotting, Western
MH  - Chymotrypsin/metabolism
MH  - Cross Reactions
MH  - Epitopes
MH  - Humans
MH  - Kallikreins/analysis
MH  - Peptide Fragments/chemical synthesis/immunology/metabolism
MH  - Prostate-Specific Antigen/*blood/chemistry/immunology/metabolism
MH  - Protein Binding
MH  - Tissue Kallikreins
EDAT- 1999/04/02 00:00
MHDA- 1999/04/02 00:01
CRDT- 1999/04/02 00:00
PHST- 1999/04/02 00:00 [pubmed]
PHST- 1999/04/02 00:01 [medline]
PHST- 1999/04/02 00:00 [entrez]
PST - ppublish
SO  - Clin Chem. 1999 Apr;45(4):486-96.