Assessing nitrate groundwater hotspots in Europe reveals an inadequate designation of Nitrate Vulnerable Zones.

Monitoring networks show that the European Union Nitrates Directive (ND) has had mixed success in reducing nitrate concentrations in groundwater. By combining machine learning and monitored nitrate concentrations (1992-2019), we estimate the total area of nitrate hotspots in Europe to be 401,000 km2, with 47% occurring outside of Nitrate Vulnerable Zones (NVZs). We also found contrasting increasing or decreasing trends, varying per country and time periods. We estimate that only 5% of the 122,000 km2 of hotspots in 2019 will meet nitrate quality standards by 2040 and that these may be offset by the appearance of new hotspots. Our results reveal that the effectiveness of the ND is limited by both time-lags between the implementation of good practices and pollution reduction and an inadequate designation of NVZs. Substantial improvements in the designation and regulation of NVZs are necessary, as well as in the quality of monitoring stations in terms of spatial density and information available concerning sampling depth, if the objectives of EU legislation to protect groundwater are to be achieved.

Patch clamp recordings of hair cells isolated from zebrafish auditory and vestibular end organs.

The senses of hearing and balance in vertebrates are transduced by hair cells in the inner ear. Hair cells from a wide variety of organisms have been described electrophysiologically but this is the first report of the application of these techniques to the genetically tractable zebrafish model system. Auditory and vestibular hair cells isolated from zebrafish lagenae and utricles were patch clamped and both inward and outward currents under voltage clamp, and changes in membrane potential under current clamp were recorded. Cells displayed substantial diversity in their morphology, constellation of channel types, and level of excitability. While all cells showed evidence of the presence of fast-inactivating (A-type) K(+) channels, other K(+) channel types, including delayed rectifier, inward rectifier and large conductance Ca(2+)-activated K(+) (BK) channels were less common. Recorded Ca(2+) currents were identified pharmacologically as L-type. Non-linear regenerative voltage responses were evoked in more than half of the cells studied.

An explorative study on the clinical utility of baseline and serial serum tumour marker measurements in advanced upper gastrointestinal cancer.

The value of early tumour marker changes during palliative chemotherapy in patients with upper gastrointestinal adenocarcinoma (UGIA) is unclear. Seventy-three patients with advanced UGIA were randomised to receive 45 mg/m2 docetaxel or 180 mg/m2 irinotecan with 5-FU/leucovorin. After every 2nd course the patients were crossed over to the other regimen. Serum was sampled before start of chemotherapy and every 2nd week during 8 weeks for CEA, TPA, TPS, CA72-4, CA19-9 and CA242 measurements. Eighteen patients (25%) had partial response (PR) and 21 patients had stable disease for at least 4 months (SD4). All baseline marker levels, except CA72-4, correlated with time to progression and survival. Patients with normal levels, except CA72-4, also had more clinical responses (PR+SD4) than patients with elevated values. Tumour marker changes early during treatment provided modest predictive information for tumour response and survival. A model combining baseline level, the change and the interaction between them gave the best prediction of outcome, however, insignificantly better than baseline level for all markers except CA242. Baseline tumour marker levels provide prognostic information for patients with UGIA on palliative chemotherapy. Early changes generally failed to provide accurate information for tumour response and survival.

Significance of serum CA125 and TPS antigen levels for determination of overall survival after three chemotherapy courses in ovarian cancer patients during long-term follow-up.

PURPOSE OF INVESTIGATION: To evaluate the prognostic significance for overall survival rate for the marker combination TPS and CA125 in ovarian cancer patients after three chemotherapy courses during long-term clinical follow-up. METHODS: The overall survival of 212 (out of 213) ovarian cancer patients (FIGO Stages I-IV) was analyzed in a prospective multicenter study during a 10-year clinical follow-up by univariate and multivariate analysis. RESULTS: In patients with ovarian cancer FIGO Stage I (34 patients) or FIGO Stage II (30 patients) disease, the univariate and multivariate analysis of the 10-year overall survival data showed that CA125 and TPS serum levels were not independent prognostic factors. In the FIGO Stage III group (112 patients), the 10-year overall survival was 15.2%; while in the FIGO Stage IV group (36 patients) a 10-year overall survival of 5.6% was seen. Here, the tumor markers CA125 and TPS levels were significant prognostic factors in both univariate and multivariate analysis (p < 0.0001). In a combined FIGO Stage III + FIGO Stage IV group (60 patients with optimal debulking surgery), multivariate analysis demonstrated that CA125 and TPS levels were independent prognostic factors. For patients in this combined FIGO Stage III + IV group having both markers below respective discrimination level, 35.3% survived for more than ten years, as opposed to patients having one marker above the discrimination level where the 10-year survival was reduced to 10% of the patients. For patients showing both markers above the respective discrimination level, none of the patients survived for the 10-year follow-up time. CONCLUSION: In FIGO III and IV ovarian cancer patients, only patients with CA 125 and TPS markers below the discrimination level after three chemotherapy courses indicated a favorable prognosis. Patients with an elevated level of CA 125 or TPS or both markers after three chemotherapy courses showed unfavorable prognosis.

TPS and CA 19-9 measurements in the follow-up of patients with pancreatic cancer and chronic pancreatitis.

The aim of this study was to assess the value of TPS and CA 19-9 in a long-term follow-up analysis of 11 patients with chronic pancreatitis (CP) and 15 patients with pancreatic cancer (PC). In all monitored patients with chronic pancreatitis the initial TPS level was below 200 U/L, whereas CA 19-9 was elevated in two of them. In one patient a dramatic increase in the TPS concentration (820 U/L) was measured at the last follow-up visit (after 8.6 months), which led to the detection of PC. In all patients with PC the preoperative TPS level exceeded 200 U/L, whereas CA 19-9 was elevated in only nine patients. After the Kausch-Whipple operation 11 patients showed no evidence of disease and in eight of these patients both TPS and CA 19-9 were within the reference range; however, in three patients liver metastases were detected after 8-24 months from the last tumor marker measurement. In four of the 15 patients both markers were elevated at the end of the follow-up period and distant metastases were clinically confirmed. Our results indicate that in patients with CP and PC undergoing long-term follow-up, TPS reflects the clinical status of patients more accurately than CA 19-9.

Vascular endothelial growth factor (VEGF) concentration in sera and tumor effusions from patients with ovarian carcinoma.

VEGF is an important angiogenic cytokine with a critical role in tumor angiogenesis. VEGF concentrations were measured using an ELISA assay, detecting VEGF165 isoform, in tumor cyst and/or ascitic fluids and in sera of 86 patients with malignant neoplasms and in 53 patients with benign ovarian neoplasms. VEGF levels were significantly elevated in the sera and cyst fluids of carcinoma patients compared with patients who had benign neoplasms. In carcinoma patients, statistically higher VEGF levels were detected in tumor effusions than in corresponding sera. The differences between VEGF values in sera and tumor effusions in relation to histological subtypes of ovarian carcinoma and FIGO stages were statistically insignificant. High VEGF levels in ascitic fluids appeared to be significantly associated with shorter disease-free survival and overall survival In multivariate analysis, besides FIGO stage and age of patients, only serum VEGF concentration was an independent prognostic factor for overall survival. The elevated VEGF levels in sera and tumor effusions of patients with FIGO stages I/II indicated that angiogenesis promoted by VEGF is a continuous process, independent of clinical advancement of the disease.

Variability of airborne cat allergen, Fel d1, in a public place.

Allergen exposure is a risk to develop an IgE-mediated sensitization. The amount of allergen inhaled per unit time should be related to the amount present in the air, i.e. airborne allergen. Thus, measuring allergen levels in the air would be more relevant than measuring allergen levels in dust. Allergens are present in the air in very minute quantities and usually become airborne after disturbance. Large variation of allergen levels have been found in dust. In this study, we measured variability of airborne cat allergen, Fel d1, in a public place using a high-volume air-sampler. We also studied the distribution and relationship between dust and airborne cat allergens in homes and schools. Air samples were collected at three different airflow rates, i.e. 55, 40, and 30 m3 of air per hour. The concentration of airborne Fel d1 in the community gymnastic hall varied from 1 to 10 pg/m3 within a period of 3 weeks, at airflow rates 55-30 m3/h. The coefficient of variation for repeated samplings was 14-43% (day-to-day variation) and 27-38% (within-day variation). As expected, higher levels of airborne cat allergens were found in homes with cats than in cat-free environments. There was a significant relationship between cat allergen levels in dust and air (r=0.7, P<0.01). Our study demonstrates that when measuring airborne cat allergen a large variation is observed within a day and between days. The large variability of measurement may be explained by the disturbance in the environments. We suggest, that when exposure assessment is made the environment in question should be analyzed, if possible in several occasions.

Tumour markers as early predictors of response to chemotherapy in advanced colorectal carcinoma.

BACKGROUND: To evaluate the reliability and validity of serum carcinoembryonic antigen (CEA), tissue polypeptide-specific antigen (TPS), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in monitoring palliative chemotherapy in advanced colorectal cancer (ACRC). METHODS: Serum was prospectively collected from 87 patients with ACRC treated with first-line 5-fluorouracil and leucovorin before and 2, 4 and 10 weeks after induction. RESULTS: Eight patients had normal baseline TPS levels, and these patients had a favourable outcome with prolonged survival and a higher rate of objective responses than patients with elevated TPS levels. At 10 weeks, all responders had a decreasing TPS value. The sensitivity for a decrease of >25% using TPS was 83% and 86% for objective and subjective responses, respectively, and the specificity was 65% and 72%, respectively. CEA had, in the same setting, a sensitivity of 45% and 46%, respectively, and the specificity was 88%. VEGF was elevated in 54% of the patients and bFGF in 15% of the patients. The VEGF values decreased during therapy in 94% of the patients, but the changes in serial VEGF values did not correlate with survival or response. Tumour markers used together did not enhance the predictive values of TPS alone. CONCLUSIONS: Repeated measurements of CEA, VEGF and bFGF in serum are of limited value in monitoring chemotherapy in ACRC. TPS seems to be of greater interest, but does not predict exactly which patients are going to have a positive outcome of palliative chemotherapy.

Immunohistochemical profiles of 30 monoclonal antibodies against cytokeratins 8, 18 and 19. Second report of the TD5 workshop.

In the first report of the TD5 workshop (TD5-1), the epitope specificities of 30 different monoclonal antibodies against cytokeratins 8, 18 and 19 were determined. This second report presents the immunohistochemical profiles of these antibodies using human appendix and normal skin for evaluation. Each antibody was tested by one or two different laboratories recruited from the Dutch Working Group on Immunohistochemistry and Cytochemistry. Eight different laboratories participated. The histological specimens were pretreated by the participants in three different ways for immunohistochemistry: microwave antigen retrieval in citrate buffer, enzymatic digestion to restore epitope exposure, no specific treatment (untreated paraffin-embedded samples), and tested blindly without knowledge of cytokeratin or epitope specificity of the antibodies at three different concentrations of 50, 10 and 1 microg/ml. Most of the tested antibodies (29/30) were useful in at least one pretreatment method, with microwave antigen retrieval being the most sensitive approach. For some antibodies, very high backgrounds were observed. Furthermore, it can be concluded that 11 MAbs performed well using all three staining protocols, including untreated paraffin-embedded sections. Interestingly, all the antibodies with documented selected specificity towards cytokeratin 8 (i.e. 178, 191, 199, 202 and 206) are reactive with an immunodominant region corresponding to amino acids 340-365 on cytokeratin 8, which evidently is well-suited as target for immunohistochemical interactions. Similarly, three antibodies with the same capacity to react with untreated samples had specificity against cytokeratin 19 (i.e. 179, 197 and 204) in the corresponding region in this filament, i.e. amino acids 311-335, or the KS 19.1 epitope. None of the six antibodies against the other major cytokeratin 19 epitope (BM 19.21) were found useful for immunohistochemistry on untreated samples. The overall conclusions from the present investigation are that all cytokeratin-8-specific antibodies with defined epitope specificities were very useful. Only one of the major two epitopes on cytokeratin 19 seems to be available for efficient immunohistochemistry. Cytokeratin 18 exposes some epitopes outside the immunodominant region reactive with the antibodies 190, 203 and 205 which can be used for untreated samples. The implications of these findings are of significance both for diagnostic histopathology and for the biology of tumor marker epitope expression in tissues.

Prognostic significance of CA 125 and TPS levels after 3 chemotherapy courses in ovarian cancer patients.

OBJECTIVE: To evaluate the prognostic significance of and predictive value for survival of CA 125 and TPS levels after three chemotherapy courses in ovarian cancer patients. METHODS: We analyzed in a prospective multicenter study the 1- and 2-year overall survival (OS) in ovarian carcinoma patients. The prognostic significance of CA 125 and TPS levels above the discrimination value (25 kU/L and 100 U/L, respectively) was examined by univariate and multivariate analyses. RESULTS: Of the 213 cases included, 64 patients were staged as FIGO I + II and 149 patients were staged as FIGO III + IV. Tumor marker levels in stage I + II were not correlated with survival. However, stage III and IV patients with elevated levels of CA 125 or TPS after three chemotherapy courses had a worse 2-year OS (69% vs 26%, P < 0.0001 and 57% vs 20%, P < 0.0001, respectively) than patients with normal levels of the markers. In univariate analysis the result of operation (staging laparatomy and partial debulking) and advanced FIGO stage (IV) were also adverse prognostic factors. Independent factors predictive of low 2-year OS by multivariate analysis were staging laparotomy, TPS elevated, and CA 125 elevated. The only factors predictive of low 1-year OS were TPS elevated and staging laparotomy. CONCLUSIONS: Ovarian cancer patients with elevated CA 125 levels after three chemotherapy courses have a poor prognosis. However, the prognostic accuracy can be significantly increased by the parallel determination of serum TPS.

Tissue polypeptide specific antigen (TPS), a marker for differentiation between pancreatic carcinoma and chronic pancreatitis. A comparative study with CA 19-9.

BACKGROUND: The value of serum tissue polypeptide specific antigen (TPS) as a complement to CA 19-9 in the detection of pancreatic carcinoma was determined prospectively. TPS and CA 19-9 levels obtained at the time of diagnosis in patients suspected of having chronic pancreatitis or pancreatic carcinoma were evaluated in receiver operating characteristic (ROC) curve analysis. METHODS: Serum TPS and CA 19-9 levels were measured by immunoassays in 122 subjects, 48 with pancreatic carcinoma and 74 with chronic pancreatitis. RESULTS: Elevated levels of CA 19-9 were detected preoperatively in 70% of pancreatic carcinoma patients and in 19% of chronic pancreatitis patients. Elevated levels of TPS were detected in 100% of patients with pancreatic carcinoma and in 22% of patients with chronic pancreatitis. The median levels of TPS and CA 19-9 for pancreatic carcinoma were significantly higher than those for chronic pancreatitis (P < 0.0001). Increasing the upper reference value of TPS allowed for better discrimination between chronic pancreatitis and pancreatic carcinoma. ROC curve analysis showed that the introduction of 200 U/L as a decision criterion for TPS did not reduce its sensitivity but significantly improved its specificity. At a specificity of 98% for TPS, discrimination between pancreatic carcinoma and chronic pancreatitis was found to be 97%. Increasing the upper reference level for CA 19-9 to attain a specificity of 98% decreased its sensitivity from 70% to 33%. CONCLUSIONS: At an elevated cut-off level for TPS (200 U/L), almost complete discrimination between pancreatic carcinoma and chronic pancreatitis was obtained. TPS will be more useful than CA 19-9 in the differential diagnosis of pancreatic carcinoma and chronic pancreatitis.

Serum levels of CA 125 and TPS during treatment of ovarian cancer.

Two hundred and sixty ovarian cancer patients (including all FIGO stages) were enrolled in a prospective multicentre study. In this interim study we analyzed 206 patients receiving combined chemotherapy for at least 3 courses for two-year overall survival (OS). CA 125 and TPS were applied for monitoring treatment and the relationship between marker levels, marker changes and clinical assessments was established. Preoperative CA 125 or TPS levels were not correlated with OS in FIGO stage I and II patients. After 3 chemotherapy courses the marker levels were not correlated with OS in stage I and II. Partial debulking in stage II patients was a bad prognostic factor. CA 125 or TPS levels (using a CA 125 discrimination level of 25 kU/l and a TPS discrimination level of 100 U/l) after 3 courses of chemotherapy were highly significantly correlated with OS in FIGO stages III and IV patients: CA 125 two-year OS 67% versus 26% (p < 0.0001) and TPS two-year OS 55% versus 22% (p < 0.0001). The prognostic value of CA 125 levels after 3 chemotherapy courses could be further increased by combining CA 125 and TPS levels. When both CA 125 and TPS levels were below their respective discrimination levels, the two-year overall survival was 75%. When both levels were above the discrimination level, the two-year overall survival was only 17%.

Use of TPS and CA 15-3 assays for monitoring chemotherapy in metastatic breast cancer patients.

TPS and CA 15-3 have been applied for monitoring treatment in patients with advanced breast cancer and the relationship between the initial marker levels and the changes of the markers during chemotherapy has been established. Both markers have demonstrated high sensitivity for detecting visceral and bone metastases in the patients (90-95%) compared to soft tissues and locally advanced disease (45-50%). The marker combination, TPS and CA15-3, showed the highest sensitivity for detecting bone/visceral metastases (98%) and soft tissue/locally advanced metastases (75%). TPS showed a more frequent decrease in marker level (> 50%) compared to CA 15-3 as well as the highest correlation (68%) to the clinically confirmed events CR, PR compared to CA 15-3 (54%). In the subgroup of metastatic breast cancer patients, demonstrating increased marker levels (> 25%) during follow-up, TPS showed the highest correlation compared to the clinically confirmed progressive disease. In the subgroup of patients with clinically confirmed progression, contemporary measurements of the marker values resulted in correlation with the clinical findings in 78% for TPS and 58% for CA 15-3. TPS appears to be superior to CA 15-3 for follow-up of metastatic breast cancer patients. TPS and CA 15-3 marker increase preceded the clinical and/or radiological signs of distant metastases in most of the patients; 1.5 and 1.1 months, respectively. The time elapsed between tumor marker increase and clinically confirmed progression was very short, which is also related to the frequent follow-up visits for metastatic breast cancer patients receiving chemotherapy. TPS appears to indicate the changes in the disease state earlier than clinical criteria or than the established tumor burden markers. The simultaneous determination of TPS and CA 15-3 provided additive information in advanced breast cancer patients and might guide management decisions in the individual patients.

Prognostic significance of CA 125 and TPS levels after chemotherapy in ovarian cancer patients.

The analysis of survival data of patients with epithelial ovarian cancer proved that both CA 125 and TPS were good markers for clinical outcome prediction. Patients receiving chemotherapy were analyzed for 2-year overall survival (OS). Kaplan-Meier survival analysis showed highly significant differences in OS between patients with stage I+II (survival for 2 years 68%) and stage III+IV (survival for 2 years 33%; p = 0.0008). CA 125 levels above or below 35 kU/I and TPS levels above or below 80 U/l after 3 chemotherapy courses were not significantly correlated with OS in stage I+II patients (p = 0.06 respectively 0.07). However, in the subgroup of patients with stage III+IV the cut-off levels of CA 125 and TPS were excellent discriminators of OS: With CA 125 levels below the cut-off 52% of the patients survived, while with CA 125 levels above the cut-off only 13% survived (p < 0.0001). With TPS levels below the cut-off 49% of the patients survived, while with levels above the cut-off only 19% of the patients survived (p < 0.0001). In the subset of patients with CA 125 levels less than 35 kU/I after 3 chemotherapy courses (n = 50) analysis of their TPS levels allowed further discrimination of the prognostic significance. With TPS levels below the cut-off 63% of the patients survived, while 35% of the patients survived with TPS levels above the cut-off. The sum value of CA 125 and TPS cut-off values (115) as discriminator correlated even better with survival rate: With levels below this sum value 63% of the patients survived, while this was only 17% with sum values above the summed cut-off level (p = 0.0004). The extent to which the tumor was removed at operation also correlated with the 2 years survival rate. None of the patients with a staging laparotomy (n = 10) showed a 2-years survival. The difference in OS between patients with complete debulking and partial debulking was significant: OS 51% versus 23% (p = 0.027). Prognosis was not significantly correlated with histological type.

Performance characteristics of IMMULITE TPS: a comparison with TPS IRMA.

This paper describes an automated immunoassay for the measurement of TPS developed for the IMMULITE. The IMMULITE system is a fully automated continous random access analyzer, which uses enzyme-amplified chemiluminiscent as the detection system. The IMMULITE TPS assay is a sequential, two-site chemiluminiscent enzyme immunometric assay designed for the quantitative measurement of TPS in serum. The IMMULITE TPS assay covers a clinical concentration range of 20-2400 U/L, with a lower detection limit of 6 U/L. A serum method comparison (n = 340) to the TPS IRMA assay demonstrates a correlation coefficient of 0.961 and a slope of 1.04. Samples run on IMMULITE TPS assay exhibit linearity upon dilution where recovered values fall within 15% of the theoretical sample value. The intra-assay precision of the IMMULITE TPS assay ranged from 3.3-4.7%, while the interassay precision ranged from 3.9-6.0%. By using different methods (immunoradiometric assay vs chemiluminiscent enzyme-labeled immunometric assay, one-step procedure vs sequential two-step procedure, manual vs fully automated procedure) the two TPS tumor marker tests used in this study gave quite comparable determinations for the sera from the cancer patients.

TPS(TM) a circulating tumor marker in breast cancer.

Tissue polypeptide specific antigen (TPS) measures an antigenic determinant associated with human cytokeratin 18. TPS is a marker of tumor cell activity in contrast to markers related to tumor burden. The value of detecting circulating TPS lies in the early detection of recurrence by serial determinations and in the rapid assessment of the efficacy of the treatment. Pretreatment levels of TPS in patients with metastatic breast cancer are related with prognosis. Decreasing TPS levels during therapy monitoring indicate response and a fast response is correlated to favourable prognosis. Increasing TPS levels, in the presence of clinically stable disease or partial remission, predict disease progression with a considerable lead-time. Improved effectiveness in breast cancer management can be seen when TPS is used in combination with CA 15-3. When tumor marker determinations are applied in a proper way in the appropriate situation, the results can assist the oncologist. Thus monitoring of therapy in patients with metastatic breast cancer should be based upon serial TPS and CA 15-3 determinations in serum. The use of tumor marker determinations in the early follow-up interval following surgery to detect early tumor recurrence may be simpler, more sensitive and less expensive than imaging methods.

The prognostic significance of increasing marker levels in metastatic breast cancer patients with clinically complete remission, partial remission or stable disease.

TPS, CA 15-3 and CEA were determined in metastatic breast cancer patients during treatment. After six months of follow-up the patients were divided into four groups according to the UICC criteria for treatment response. Forty-six patients with a more favorable prognosis (complete remission, partial remission or stable disease) were followed for an extended period. In 30 of the 46 patients at least one marker had increased at the end of the six-month period by at least 25% (TPS in 54%, CA 15-3 in 20%, CEA in 20%). All these 30 patients subsequently developed progression. The prognostic sensitivity was 83%, 30% and 30%, respectively, for TPS, CA 15-3 and CEA. The combination of TPS and CA 15-3 showed a sensitivity of 96%. The median lead time was about 8 months for TPS and CA 15-3, but less than 50% of the patients showed a lead time for CA 15-3 as compared to TPS. We conclude that TPS and CA 15-3 determinations are helpful for the prediction of progression during the follow-up of breast cancer patients.

In-house reference (IHR) preparation of Candida albicans allergen extract. A standardized extraction procedure.

A standardized, controlled procedure for preparation of an in-house reference (IHR) preparation of an allergen extract of Candida albicans is described. The procedure, based on previous studies of allergens of C. albicans, is designed to yield a maximum of allergens in optimum extraction conditions and to provide a reference preparation for further extract production. The SDS-PAGE, IgE-immunoblotting, and crossed radioimmunoelectrophoresis (CRIE) analyses showed that the procedure is reproducible with acceptable batch-to-batch variation. The variation in the content of the most important allergens, namely, proteins with molecular weights of 46, 29, and 27 kDa in the pooled final batches, is acceptable (coeff. of variation < 15%), although in the intermediate batches of different strains, the coefficient of variation may occasionally exceed 20%. A comparison with other C. albicans allergen preparations used in our previous studies is also presented. The resulting extract can be used as a reference in further extract production and also in experimental in vitro and in vivo studies.

Epitope specificity of 30 monoclonal antibodies against cytokeratin antigens: the ISOBM TD5-1 Workshop.

The epitope specificities of 30 monoclonal antibodies (MAbs) against the most common human cytokeratins. i.e., Nos. 8, 18, and 19, in epithelial cells were investigated in the ISOBM TD-5 Workshop. Seven research groups from universities or companies participated independently in the evaluation of the antibody specificities. The complex assembly of cytokeratins in vivo, with obligatory heterologous dimeric combinations of different cytokeratins from each of the two major groups, comprising together more than 20 different individual cytokeratins, made analysis of the antibody reactivity patterns with isolated single cytokeratins necessary. The concordance of the evaluations was striking and independent of the technologies used. As antigens purified individual cytokeratins, chemically degraded purified cytokeratins, recombinant intact and truncated cytokeratins, as well as specific synthesized shorter peptides were used. In order to elucidate the epitope specificity, reactivity patterns in ELISA assays and immunoblots with partial enzymatic degradation of the antigens were performed. Competitive cross-inhibition experiments between antibodies using antigens and antibodies in all possible combinations were performed with radioimmunometric assays, BIAcore, and ELISA technology. All 30 antibodies could convincingly be classified with regard to target cytokeratin. One MAb (192) had to be deleted due to dual specificities in both isotype and epitope specificity against its target. Six antibodies bound selectively to cytokeratin 8, 14 to cytokeratin 18, and 10 to cytokeratin 19, as demonstrated by using native, recombinant, and synthesized antigens. The immunodominant part of the molecule for all three types of cytokeratins was located in the region of amino acid (aa) 270-400. Out of the six MAbs reactive with cytokeratin 8, four MAbs, i.e., 178, 199, 202, and 206, were reactive with a sequence in the interval aa 340-365, and MAb 191 reacted with a closely related epitope. The remaining antibody, 192, presented dual specificities. At least two closely related major immunogenic epitopes could be identified in cytokeratin 8. In cytokeratin 18 four distinct epitopes could be documented, again with the dominating sequence region 270-429 as target for 10 (181, 184, 186, 188, 189, 190, 193, 196, 198, and 200) out of 14 antibodies. Since MAb 193 is known to react with the M3 epitope, aa 322-342 in cytokeratin 18, this entire group is reactive in the region close to the charge shift, in the middle of the rod 2B region, as shown by competitive binding. The remaining four anticytokeratin 18 antibodies (180, 185, 203, and 205) displayed unique, noncompetitive binding to this filament. Cytokeratin 19, reactive with altogether ten antibodies, displayed two major epitopes, all of them also within the large immunodominant region. MAbs 179, 195, 197, and 204 were reactive with the peptides aa 311-335 also known as the KS 19.1 epitope, and MAbs 182, 183, 187, 194, and 201 bound to peptide aa 346-367, known as the BM 19.21 epitope. One antibody, 231, was selectively reactive with aa 356-370 in cytokeratin 19. A complex pattern of binding specificities comprising at least ten different, noncompetitive epitopes, mainly situated in the rod portion, 2A and 2B, situated close to the charge shift in the rod of all three cytokeratins was documented. Out of the 29 classifiable antibodies, altogether 22 were reactive in this very short region, i.e., from aa 311 to 370 in all cytokeratin filaments. The remaining seven antibodies displayed unique binding properties. The implications of the findings are of significance both for immunohistochemistry and for assaying circulating heterodimeric, partially degraded complexes in patients' blood for tumor marker evaluation.

Tissue polypeptide specific antigen (TPS) detects a specific epitope structure on human cytokeratin.

A TPS-reactive protein fragment from a human colon adenocarcinoma cell line was purified to electrophoretic homogeneity. N-terminal sequence analysis of the purified 13 kDa protein fragment demonstrated that the component was a fragment of human cytokeratin 18. The M3 monoclonal antibody (detector antibody in the TPS assay) was applied for screening of an expression library. The M3-reactive phage clones were subcloned and PCR amplified. DNA-sequence analysis revealed it to contain a nucleotide fragment corresponding to human cytokeratin 18. Smaller fragment, engineered by PCR and expressed as fusion proteins, demonstrated that the M3 epitope is localized to human cytokeratin 18, amino acid residues 322-340.