| Patients with cancer frequently develop autoantibodies, however the mechanism by which autoimmunity develops and the signigicance of these antibodies in these patients is uncertain.Are these autoantibodies immunologic footprints of previous biological events, as has been suggested for the antinuclear antibodies found in the systemic autoimmune diseases, or are they largely irrelevant to the process of oncogenesis? Our work and that of others suggest that the humoral immune response directed against tumor cell appears to be characteristic of many cancers, and perhaps in some cases tumor specific antigens may play a causative role in the process of tumorigenesis. Based on this hypothesis, we have detected autoantibodies in 8 kinds of common malignancies on cellular level and protein level with indirected immunofluorescence(IIF) as well as immunoblotting, and compared their autoantibody profiles with those of normal people and those of common autoimmne disease. Also we have developed a new approach to identify a pancreatic cancer associated autoantigen(PAA47). To further the understanding of it's clinical value in pancreatic cancer , we have cloned it's encoding sequence and constructed a prokaryotic expression vector pQE30-PAA47 and gained fusion protein PAA47 from Ecoli.M15. Here we will summary our experiments as five parts in more details.l).To get some information about the positive rates of autoantibodies in malignancies and fluorescence patterns as well as the locations of their target antigens in cells, sera of 423 patients with malignancies (65 with hepatocellular carcinoma, 77 with lung cancer, 81 with gastric carcinoma, 82 with colonrectal cancer,55 with pancreatic cancer,24 with breast cancer,25 with ovary cancer, 14 with bladder carcinoma) as well as 140 healthy controls were detected with IIP. Results showed that the positive rate of autoantibodies in patient group and normal group was 54.85% and 17.14% respectively. Although both groups had higher positive rates with the growth of age (P<0.05), the positive rates of cancer groups were higher than that of normal group significantly in each age group(P<0.01). Besides the significant difference in positive rates, cancer group showed different fluorescence pattern and antigen location in cells with those of control (P<0.05).At the same time , there was no significant difference among 8 cancer groups(P>0.05).2). Using ENA immunoblotting kits, 95 sera of patients .which showed autoantibody positive in IIP, were detected.lt demonstrated that 90 sera showed one or more positive bands in ENA test. Some of them could be confirmed as known autoantibodies .which mainly appear in certain autoimmune diseases(2 of anti-PM-SCL, 7 of anti-Ku,5 of anti-CENP, 9 of anti-M2, 4 of anti-RNP.7 of anti-SS-A ,1 of anli-Jo-1,5 of anti-SS-A/SS-B and 4 of anti-Rib-P-Protein). There were also many positive bands which may represent unknown autoantibodies that could not be demonstrated with ENA kits. To further probing autoanbody repertoire in malignancies, we established immunoblotting method with the whole celluar extract of Hep-2 as antigen substrate and detect sera of 227 patients as well as the sera of 48 healthy controls. One or more positive bands could be observed in each 209 cancer patients (77.12%) .which was significantly higher than what have been observedin normal group(50. 00%) (P<0.01). The distribution of antigen molecular mass varied from 20 KDa to 170 KDa, which was more broader than that of controls. It was noticeable that several common positive bands had been observed in some certain cancer groups. Out of 56 sera of lung cancer patients, 38(67. 85%) had a common positive band with related molecular weight about 65KDa, while in 16.67% (8/48) normal group. 46.43% (26/56) lung cancer patients had a common positive band with related molecular weight about 45KDa, which could be abserved in none of the 48 normal subjects .Altogether there were 4 common positive bands observed in colonrectal cancer patients, which include 90KDa(31/50) , 70KDa(34/50), 5...
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