Interaction of Rheumatoid Factor with Immobilized ss-DNA

Rheumatoid factors(RFs) are the characteristic autoantibodies of rheumatoid arthritis. Recent researches in our laboratory showed that the immobilized single-stranded DNA(ss-DNA) immunoadsorbent can selectively remove RFs from the serum of patients. In the present paper are studied the modification of argininine, tryptophan, lysine residues and carboxyl terminus of IgGRF, which was separated from patients′ serum, with 1,2-cyclohexanedione(CHD), N-bromosuccinimide(NBS), pyridoxal 5′-phosphate(PP) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(EDC) respectively, and their effects on the adsorption capacity of the immobilized ss-DNA immunoadsorbent for IgGRF. After the specific modification, the corresponding adsorption capacities of the adsorbents were changed from 48%, 46%, 44% and 54% to 84%, 14%, 21% and 81%, respectively. These results indicate that the electrostatic or ionic-bonding is essential for the interaction between ss-DNA and IgGRF.

DETECTION OF VEGF LEVELS IN ASCITES AND PERITONEAL FLUID

Objective: The expression of vascular endothelial growth factor (VEGF) is correlated to the invasion and metastasis of tumor cells in many clinical carcinomas. In this study, we detected soluble VEGF levels in ascites and peritoneal fluid and explored its clinical significance. Methods: A total of 91 samples were collected and divided into 5 experimental groups: petitoneal fluid of patients with benign (n=10) and malignant disease (n=14), cirrhotic ascites (n=36), tuberculous ascites (n=8) and malignant ascites (n=23). Using a sandwich enzyme-linked immunoadsorbent assay, the concentration of soluble VEGF was measured in ascites (n=67) and petitoneal fluid (n=24). Results: VEGF levels in malignant ascites were 640.74264.81 pg/ml, significantly higher than those in cirrhotic ascites, tuberculous ascites and peritoneal fluid of patients with benign and malignant disease (P<0.01, separately). However, the difference of VEGF levels among the latter 4 groups had no statistic significance (P>0.05), separately). Furthermore, VEGF levels in malignant ascites from patients with ovarian cancer were higher than those with gastric and colon cancer (P<0.01, respectively), while there was no significant difference between gastric cancer and colon cancer (P>0.05). Using VEGF level of 118.96 pg/ml as a minimum cutofflimit, the sensitivity and specificity of VEGF of this assay to diagnose malignant ascites were 91.3% and 73.9% respectively. Conclusion: The elevated levels of VEGF may be useful as an index in differential diagnosis of benign and malignant ascites. It appears that VEGF plays an important role in malignant ascites formation.

MODIFICATION OF TRYPTOPHAN RESIDUES OF IgGRF AND ITS EFFECT ON THE ADSORPTION CAPACITY

Tryptophan residues of IgGRF from rheumatoid arthritis patient were modified with N-Bromosuccinimide (NBS) and the product of modification was characterized by UV-spectrum、Fluorescence emission spectrum and CD-spectrum. The corresponding adsorption capacity of immobilized ssDNA immunoadsorbent for IgGRF was enhanced from 46% to 86%, This result indicates the tryptophan residue is essential for the interaction between ssDNA and IgGRF .and ionic-bonding plays an important role in adsorption.