Age dependence of tissue plasminogen activator concentrations in plasma, as studied by an improved enzyme-linked immunosorbent assay
Rånby, M.; Bergsdorf, N.; Nilsson, T.; Mellbring, G.; Winblad, B.; Bucht, G.
Clinical Chemistry 32(12): 2160-2165
1986
ISSN/ISBN: 0009-9147 PMID: 3096611 Document Number: 276858
A procedure for improving the specificity of enzyme-linked immunosorbent assays (ELISA) was devised, based on addition of antigen-specific or non-immune immunoglobulins to the citrated plasma sample and defining the difference in assay response between these two mixtures as the antigen-specific part of the response. When applied to measurement of tissue plasminogen activator (t-PA; EC 3.4.21.31) antigen in plasma, this procedure resulted in elimination of the overestimates obtained in a large proportion (10-20%) of patients' samples when assayed according to the conventional ELISA technique. Basal t-PA concentrations in plasma were found to be highly age-dependent, normal values being about 3 micrograms/L for adults near 30 years of age and about 10 micrograms/L for those over 60. Patients with gallbladder stone disease had increased mass concentrations of t-PA in plasma, even when corrected for the age effect; patients with multi-infarct dementia did not.