title: Low serum alpha-1-antitrypsin specific activity in monoclonal gammopathies.
abstract: BACKGROUND
  Serum alpha 1-antitrypsin (alpha 1AT) antigen concentration is elevated in malignancies as the result of acute phase reaction. In the present study, we examined whether the alpha 1AT elevation in monoclonal gammopathies was accompanied by an adequate increase of its functional activity.
  
  
  METHODS
  In this case-control study, serum alpha 1AT concentration was measured in 187 ambulatory patients with monoclonal gammopathies and 320 healthy blood donors matched according to sex and age. The alpha 1AT antigen concentration was assayed by immunonephelometry, whereas its functional activity was measured as trypsin inhibitory capacity (TIC). The specific alpha 1AT inhibitory activity (SIA) was calculated, defined as the TIC/antigen concentration ratio.
  
  
  RESULTS
  The alpha 1AT antigen concentrations obtained in the patients' samples were very significantly higher as compared with the corresponding values in the control group (mean +/- SD = 134 +/- 41.9% of normal, p < 0.001). However, the TIC values were higher in the patients than in the healthy controls only by 4% (104 +/- 23.8%, p < 0.05). The specific alpha 1AT activity was very significantly lower in the patients, as compared with the controls (p < 0.001), indicating that serum alpha 1AT in monoclonal gammopathies was partially inactive.
  
  
  CONCLUSIONS
  As poor correlation between the TIC values and the antigen concentrations was obtained in the patient group as well as the decreased specific alpha 1AT activities, the TIC values in patients with monoclonal gammopathies should be interpreted with caution.
authors.affiliation: Department of Medical Biochemistry, University School of Pharmacy, Belgrade, Serbia, Republic of Yugoslavia.
authors.forename: Z
authors.initials: Z
authors.lastname: Jelić-Ivanović
authors.forename: B
authors.initials: B
authors.lastname: Stanković
authors.forename: A
authors.initials: A
authors.lastname: Topić
authors.forename: V
authors.initials: V
authors.lastname: Spasojević-Kalimanovska
authors.forename: S
authors.initials: S
authors.lastname: Spasić
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D010265:Paraproteinemias / Q000097:blood*; D012016:Reference Values; D014357:Trypsin / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000032:analysis*
chemical_list: D000515:alpha 1-Antitrypsin; D014357:Trypsin