Multicentric evaluation of a second generation assay to detect antiviral citrullinated peptide antibodies: a collaborative study by the Forum Interdisciplinare per la Ricerca nelle Malattie Autoimmuni.

AIMS: A novel immunoenzymatic assay using viral citrullinated peptides derived from Epstein-Barr virus-encoded proteins (viral citrullinated peptide 2 (VCP2)) has been developed and evaluated by means of a multicentre collaborative study. METHODS: Three hundred nine sera from patients with established rheumatoid arthritis (RA), 36 with early arthritis, 12 with juvenile arthritis and 453 controls were tested for VCP2 and cyclic citrullinated peptide (CCP) antibodies. RESULTS: The VCP2 assay showed 78.3% sensitivity and 97.1% specificity. VCP2 and CCP had a high concordance rate in patients with RA (88%) and controls (97%). However, 36 RA sera were positive in the CCP assay but negative on VCP2, and two RA sera reacted only on VCP2. CONCLUSIONS: The new VCP2 assay is endowed with high sensitivity and specificity. VCP2-positive RA sera are mostly but not completely contained in the CCP-positive population. Studies are in progress to establish whether the VCP2 assay can detect clinically distinct subsets of patients with RA.

Antiprothrombin antibodies: a comparative analysis of homemade and commercial methods. A collaborative study by the Forum Interdisciplinare per la Ricerca nelle Malattie Autoimmuni (FIRMA).

OBJECTIVE: Prothrombin (PT) is a target for antibodies with lupus anticoagulant (LA) activity, suggesting the possible application of anti-prothrombin antibody (aPT) assays in patients with antiphospholipid syndrome (APS). Different methods - both homemade and commercial - for the detection of aPT are available, but they seem to produce conflicting results. The purpose of this study was to compare the performance of different assays on a set of well-characterized serum samples. PATIENTS AND METHODS: Sera were gathered from 4 FIRMA institutions, and distributed to 15 participating centres. Forty-five samples were from patients positive for LA and/or anticardiolipin antibodies (aCL) with or without APS, and 15 were from rheumatoid arthritis (RA) patients negative for antiphospholipid antibodies. The samples were evaluated for IgG and IgM antibodies using a homemade direct aPT assay (method 1), a homemade phosphatidylserine-dependent aPT assay (aPS/PT, method 2), and two different commercial kits (methods 3 and 4). In addition, a commercial kit for the detection of IgG-A-M aPT (method 5) was used. RESULTS: Inter-laboratory results for the 5 methods were not always comparable when different methods were used. Good inter-assay concordance was found for IgG antibodies evaluated using methods 1, 3, and 4 (Cohen k > 0.4), while the IgM results were discordant between assays. In patients with thrombosis and pregnancy losses, method 5 performed better than the others. CONCLUSION: While aPT and aPS/PT assays could be of interest from a clinical perspective, their routine performance cannot yet be recommended because of problems connected with the reproducibility and interpretation of the results.

Circulating CA 549 and other associated antigens in breast cancer patients.

The new marker CA 549 was determined in the serum of 258 breast cancer patients, classified according to TNM (148 at diagnosis and 110 at relapse), using a RIA method (cut-off: 10 U/ml). CEA, CA 15-3 and MCA were also evaluated. At diagnosis, CA 549 was more sensitive than the other markers, and cut-off values of 11 and 12 U/ml did not significantly reduce sensitivity. No significant correlation existed between the markers, except for CA 15-3 and CA 549 (r = 0.65). A new quantitative approach to the four markers was effected in the relapsed patients: an X value was calculated for each marker by dividing serum concentration by its cut-off. In these patients, grouped according to the area involved, marker sensitivities were similar except in locoregional relapse, where CA 549 and MCA were the most sensitive. From the data obtained, the more defined cut-off and the good specificity, it is suggested that CA 549 be routinely determined in the follow-up of the disease.

Tumour associated antigens CA 15.3 and CA 125 in ovarian cancer.

CA 125 and CA 15.3 antigens were determined by enzyme immunoassay in 78 patients with ovarian cancer for a total of 540 determinations. The antigens were also investigated in sera from 100 women with other gynaecological diseases, 82 lung cancer patients and in 39 pleural fluids of varying origin. CA 15.3 reference values were evaluated in 91 healthy women (cut-off: 25 U/ml). CA 15.3 sensitivity at diagnosis (60%) and for detecting relapse (44%) was lower than that of CA 125 (90% and 64.7%, respectively). However, CA 15.3 does not increase with aspecific mesothelial cell reaction and thus it is more specific than CA 125. Combined use of the markers during follow-up improves early detection of relapse (at least one of the two was positive in 79% of cases). Therefore both CA 15.3 and CA 125 should be routinely determined for the detection and monitoring of ovarian cancer.

Efficiency of composite laboratory tests in the diagnosis of liver malignancies.

The utility of the markers CEA, beta-HCG, CA-50, alpha-fetoprotein (APF), ferritin, alkaline phosphatase (AP), its isoenzyme liver-1 (APL1), gamma-glutamyltransferase (gGT), its fast migrating isoenzyme (gGT1) and 5'nucleotidase (5'N) in differentiating liver malignancies and benign involvement was evaluated in the sera of 85 patients with hepatocellular carcinoma (HCC), 157 with chronic liver disease (CLD) and 91 with liver metastases (LM) derived from different tumors. The mean concentrations of all the parameters except CEA and GGT1 were significantly different in HCC and CLD, but a broad overlap existed in the two groups, so different cut-offs were considered to assess the positive and negative predictive values and test efficiency (Eff). The best results were observed considering AFP greater than 100 IU/m (Eff0.86), ferritin greater than 800 ng/ml (Eff0.69), CA-50 greater than 100 U/ml (Eff 0.63), beta-HCG greater than 10 mU/ml (Eff 0.61), AP greater than 300 IU/ml (Eff 0.66), the presence of APL1 (Eff 0.78), 5'N greater than 25 mU/ml (Eff 0.70), gGT greater than 100 mIU/ml (Eff 0.63). Among HCC patients 17% did not secrete AFP; in 26% the protein was less than 100 IU/ml and in 36% less than 400 IU/ml. Apart from AFP the most effective marker was APL1. At the above cut-offs more than three parameters were simultaneously positive in 71% of HCC and 9.9% of CLD. CEA, CA50, AFP were the only parameters that distinguished the HCC from the LM group; in the latter, APL1 was also a very sensitive marker (87%) for neoplastic involvement of the liver.

Detection of malignant pleural effusions by tumor marker evaluation.

Cytologic examination and determination of tumor markers (PHI, LDH, alpha-1-glycoprotein, alpha-2-HS-glycoprotein, beta 2-microglobulin, ferritin [corrected], sialic acid, IgE, fetoprotein, CEA, beta HCG and beta 1-SP-glycoprotein) were carried out in pleural fluid samples obtained from 70 patients with suspected neoplasia. Tumor markers were also determined in sera. The protein content of all pleural effusions was greater than or equal to 3 g/dl. Patients were grouped according to diagnosis as follows: (a) 42 with neoplastic diseases (7 mesotheliomas and 19 lung, 4 ovarian, 3 breast and 8 miscellaneous cancers), (b) 22 with benign inflammations and (c) 6 with congestive effusions. Of the parameters examined, only CEA and beta-HCG [corrected] gave information that the effusion was probably malignant. Using 6 ng/ml as cut-off for CEA and 10 mIU/ml for beta HCG, the sensitivity was 57.1% and 45.2%, respectively, specificity was 92.8% for both parameters and test efficiency 0.75 and 0.69, respectively. When CEA and beta HCG were considered together sensitivity increased to 73.8% and efficiency to 0.78. CEA and/or beta HCG were positive in the pleural effusions of 19 of the 20 malignant pleural effusions, all with a negative cytologic examination, which subsequently became positive in 8. Because of their high specificity, these two parameters are a useful tool and can be routinely measured to evaluate pleural effusions of dubious origin, even if CEA and beta HCG cannot, on [corrected] their own, define the primary malignancy.

Beta-2-microglobulin as a tumor marker in solid malignancies.

Beta-2-microglobulin (beta 2-MG) and CEA were measured in the sera of 186 cancer patients divided into two groups: at diagnosis (D) and at follow-up (F). Four groups of patients at diagnosis (D-I, D-II, D-III and D-IV according to TNM classification) and two at follow-up (in remission, F-RS, and in relapse, F-RP) were considered. All patients had normal serum creatinine and urea concentrations. beta 2-MG values in D-I were significantly (p less than 0.01) lower than those for D-II and D-III, while in D-IV they overlapped those of group D-I. No significant difference was observed between F-RS and F-RP patients. Patients with serum CEA concentration greater than 100 ng/ml revealed beta 2-MG values close to those of groups D-I and D-IV. In 10% of patients in stage IV or with CEA greater than 100 ng/ml beta 2-MG was lower than the mean value of the healthy population. From data beta 2-MG is probably produced by an aspecific reaction to the tumor and the decrease in advanced stages could express a decreased immunologic response. On the other hand, high serum beta 2-MG in the initial stages of the neoplasia may reflect an elevated cell turnover, while low beta 2-MG during the final stages may be due to a weak expression of the protein by highly undifferentiated cells.

Variations in alpha-2-HS glycoprotein level in neoplastic disease with and without involvement of bone.

Variations in the serum level of alpha-HS-glycoprotein may be observed in all pathological conditions which induce changes in bone turn-over, as well as in inflammatory and neoplastic diseases. This study includes 162 patients divided into four groups according to the TNM classification (tumour, lymph node metastasis). The first consisted of patients with neoplasms at TNM stages 1 and 2 with no bone metastases; the second of similar patients at TNM stages 3 and 4. The third group were patients with primary or secondary neoplasms of bone, and the fourth were patients with viral or bacterial diseases. The levels of alpha-2-HS-glycoprotein serum were determined for all the groups and these were compared with AAG (alpha-1-glycoprotein) and CEA (carcinoembryonic antigen). There were no significant differences in the levels of alpha-2-HS-glycoprotein for the first group as compared with normal controls, while in the other groups the differences were significant. The levels of alpha-2-HS-glycoprotein were diminished when the levels of CEA and AAG were both high, but increased when only one of these other parameters was high.