Immunological measurement of transforming growth factor-beta 1 (TGF-beta1) in blood; assay development and comparison.
Development of a new, sensitive immunoassay for measuring transforming growth factor beta 1 (TGF-beta1) is described and compared with four commercially available TGF-beta1 immunoassays. Preanalytical conditions were evaluated. The nonlinearity found in serum or plasma is due to masking of TGF-beta1 by binding proteins in blood. Mixing TGF-beta1 with latency-associated peptide or alpha2-macroglobulin at physiological concentrations suppressed most of the TGF-beta1 signal. Plasma fibronectin showed no effect, even at concentrations exceeding its physiological range. Equilibrium concentrations computed from a model system confirmed the experimental results. Dilutional nonlinearity could be markedly reduced by an appropriately designed activation procedure that minimized the effects of reassociation between TGF-beta1 and its binding partners during restoration of a neutral pH. Plasma should be used for measuring TGF-beta1 in blood. Because serum TGF-beta1 is highly significantly correlated with the platelet count, probably most of the TGF-beta1 is released by platelet degranulation.
Kropf
J
J
Department of Clinical Chemistry and Central Laboratory, Philipps University, Marburg, Germany. kropf@mailer.uni-marburg.de
Schurek
J O
JO
Wollner
A
A
Gressner
A M
AM
D003429:Cross Reactions; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D007700:Kinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016212:Transforming Growth Factor beta / Q000097:blood*; D000511:alpha-Macroglobulins / Q000378:metabolism
D005353:Fibronectins; D016212:Transforming Growth Factor beta; D000511:alpha-Macroglobulins