Most of complicated or semiquantitative factor XIII assay techniques are unsuitable for the purpose of quantitative assay in routine laboratories. However, now assay system developed by us requires only simple procedures and show high sensitivity and reproducibility. The principle of our method is as follows: Haet-defibrinated plasma is treated with casein, calcium, thrombin and dansylcadaverine (DC) and then maleimid is added to stop the incorporation reaction. Thereafter, the reaction mixture is gel-filtrated by Toyopearl (HW-40) mini column for the separation of DC-casein from free DC. With the excitation and emmition wavelengths fixed at 355nm and 525nm respectively, the fluorescence intensity is measured. The values of fluorescence intensity subtracted substrate blank are proportional to factor XIII activity. Comparative study was made between our method and Lorand's method and Laurell's method In twenty cases of normal subject and twenty cases of DIC, our method and Lorand method showed a good correlation. Our assay technique is simple and it requires only a couple of hours for a whole course of the assay. Moreover, the detectable limit, if necessary, can be brought to lower range than one percent by increasing the sample amount, elongating reaction time and subtracting plasma blank.
