Studies on the discrepancy of results of FDP obtained by HIT and SCT in the cases with nephritis

Abstract

The FDP in blood was assayed in 24 patients with nephritis by both methods of hemagglutination inhibition test (HIT) and staphylococcal clumping test (SCT). In cases with nephritis, a remarkable discrepancy between SCT and HIT values was observed, having the ratio with SCT to HIT of 7.8, whereas this ratio was 1.7 in other diseases, such as liver cirrhosis, purpura, cancer or hypertrophy of prostata, leukemia, myocardial infarction, pregnancy, Abruptio placentae and others (Fig. 1). The discrepancy was generally more pronounced in the active phase of nephritis than in the phase of remission. As these results seemed to be indicative for the significance in clinic as well as phathophysiology of nephritis, more studies in vitro were carried out in this report.Three kinds of samples such as patient's plasma with high discrepancy (ratio 8.0), normal plasma and plasmin digested normal plasma (TP-plasma) by the addition of thrombin and plasmin were flowed through DEAE Sephadex A-50, respectively. The TP-plasma was obtained by the procedure in which normal plasma was incubated with 0.02 units of thrombin for 5min at 37°C, followed by the incubation with 0.5 units of plasmin for 15min (Fig. 4). In the elution of patient's plasma through DEAE Sephadex A-50, the fraction giving storongly positive SCT but negative HIT was obtained at the gradient of 200mM NaCl (Fig. 2) from TP-plasma (Fig. 5). However, this fraction could not be obtained by the column procedure for untreated normal plasma (Fig. 3). These results indicated that the plasma of cases in active phase of nephritis might involve lot amount of soluble fibrin.Further studies had been carried out by using soluble fibrin by Felten's method or fibrin monomer by Largo's method.The soluble fibrin obtained by the former method in which thrombin treated EDTA plasma was precipitated by 50% ethanol in saline, gave positive SCT (640μg/ml) and negative HIT (below 20μg/ml). The fibrin monomer obtained by the latter method which was started from purified fibrinogen, followed by defibrination with thrombin, disolution in 5M Urea and purification by precipitation, gave no discrepancy between the result on SCT and HIT.According to our present results, it could be assumed as follows. The soluble fibrin which was made in vitro experiments showed the similar pattern to the plasma of nephritis, having discrepancy between SCT and HIT. However the purified fibrin monomer failed to show the remarkable discrepancy between them. The present results would indicate that the soluble fibrin or soluble fibrin-fibrinogen complex might contribute to the significance in FDP assay for cases with nephritis.