AUTORADIOGRAPHIC METHOD FOR QUANTITATION OF RADIOLABELED PROTEINS IN TISSUES USING IN-111

  • 1 September 1989
    • journal article
    • research article
    • Vol. 30  (9) , 1538-1545
Abstract
A quantitative autoradiographic method was developed to measure 111In-labeled proteins in extravascular tissues with a spatial resolution sufficient to associate these proteins with tissue morphology. A linear relationship between measured grain density and isotope concentration was demonstrated with uniformly-labeled standard sources of epoxy-embedded gelatin containing [111In]albumin; half-distance of spatial resolution was 0.6 .mu.m. The technique was illustrated by measuring 24-hr accumulation of diethylenetriaminepentaacetic acid-coupled 111In-labeled human polyclonal IgG and human serum albumin (HSA) in a thigh infection model in the rat. Gamma camera images localized the infection and showed target-to-background ratios of 2.5 .+-. 0.3 for IgG and 1.4 .+-. 0.02 for human serum albumin (mean .+-. s.d., n = 3). Using quantitative autoradiography, significantly higher average tissue concentrations were found in the infected thighs at 4 to 4.5% of the initial plasma concentrations as compared to 0.2 .+-. 0.3% of initial plasma concentrations in the noninfected thigh (P < 0.05); these radiolabeled proteins were not inflammatory cell associated and localized primarily within the edematous interstitial spaces of the infection.