Foetal antigens and their role in the diagnosis and clinical management of human neoplasms: a review

Cancer Vaccines: Promising Therapeutics or an Unattainable Dream

The advent of cancer immunotherapy has revolutionized the field of cancer treatment and offers cancer patients new hope. Although this therapy has proved highly successful for some patients, its efficacy is not all encompassing and several cancer types do not respond. Cancer vaccines offer an alternate approach to promote anti-tumor immunity that differ in their mode of action from antibody-based therapies. Cancer vaccines serve to balance the equilibrium of the crosstalk between the tumor cells and the host immune system. Recent advances in understanding the nature of tumor-mediated tolerogenicity and antigen presentation has aided in the identification of tumor antigens that have the potential to enhance anti-tumor immunity. Cancer vaccines can either be prophylactic (preventative) or therapeutic (curative). An exciting option for therapeutic vaccines is the emergence of personalized vaccines, which are tailor-made and specific for tumor type and individual patient. This review summarizes the current standing of the most promising vaccine strategies with respect to their development and clinical efficacy. We also discuss prospects for future development of stem cell-based prophylactic vaccines.

Cancer vaccines: Looking to the future

These are exciting times for the field of cancer immunotherapy. Although the clinical efficacy of monoclonal antibodies has been demonstrated since the early 1990s, the therapeutic profile of other immunotherapeutic approaches-especially vaccines-has not yet been formally clarified. However, the recent success of several immunotherapeutic regimens in cancer patients has boosted the development of this treatment modality. These achievements stemmed from recent scientific advances demonstrating the tolerogenic nature of cancer and the fundamental role of the tumor immune microenvironment in the suppression of antitumor immunity. New immunotherapeutic strategies against cancer attempt to promote protective antitumor immunity while disrupting the immunoregulatory circuits that contribute to tumor tolerance. Cancer vaccines differ from other anticancer immunotherapeutics in that they initiate the dynamic process of activating the immune system so as to successfully re-establish a state of equilibrium between tumor cells and the host. This article reviews recent clinical trials involving several different cancer vaccines and describes some of the most promising immunotherapeutic approaches that harness antitumor T-cell responses. In addition, we describe strategies whereby cancer vaccines can be exploited in combination with other therapeutic approach to overcome-in a synergistic fashion-tumor immunoevasion. Finally, we discuss prospects for the future development of broad spectrum prophylactic anticancer vaccines.

Selective activation of trophoblast-specific PLAC1 in breast cancer by CCAAT/enhancer-binding protein beta (C/EBPbeta) isoform 2

The trophoblast-specific gene PLAC1 (placenta-specific 1) is ectopically expressed in a wide range of human malignancies, most frequently in breast cancer, and is essentially involved in cancer cell proliferation, migration, and invasion. Here we show that basal activity of the PLAC1 promoter is selectively controlled by ubiquitous transcription factor SP1 and isoform 2 of CCAAT/enhancer-binding protein beta that we found to be selectively expressed in placental tissue and cancer cells. Binding of both factors to their respective elements within the PLAC1 promoter was essential to attain full promoter activity. Estrogen receptor alpha (ERalpha) signaling further augmented transcription and translation of PLAC1 and most likely accounts for the positive correlation between PLAC1 expression levels and the ERalpha status we observed in primary breast cancer specimens. DNA affinity precipitation and chromatin immunoprecipitation assays revealed that transactivation of the PLAC1 promoter by ligand-activated ERalpha is based on a nonclassical pathway independent of estrogen-response elements, by tethering of ERalpha to DNA-bound CCAAT/enhancer-binding protein beta-2, and SP1. Our findings provide first insight into a novel and hitherto unknown regulatory mechanism governing selective activation of trophoblast-specific gene expression in breast cancer.

A placenta-specific gene ectopically activated in many human cancers is essentially involved in malignant cell processes

The identification and functional characterization of tumor-specific genes is a prerequisite for the development of targeted cancer therapies. Using an integrated data mining and experimental validation approach for the discovery of new targets for antibody therapy of cancer, we identified PLAC1. PLAC1 is a placenta-specific gene with no detectable expression in any other normal human tissue. However, it is frequently aberrantly activated and highly expressed in a variety of tumor types, in particular breast cancer. RNAi-mediated silencing of PLAC1 in MCF-7 and BT-549 breast cancer cells profoundly impairs motility, migration, and invasion and induces a G1-S cell cycle block with nearly complete abrogation of proliferation. Knockdown of PLAC1 is associated with decreased expression of cyclin D1 and reduced phosphorylation of AKT kinase. Moreover, PLAC1 is localized on the surface of cancer cells and is accessible for antibodies which antagonize biological functions of this molecule. These features, in summary, make PLAC1 an attractive candidate for targeted immunotherapeutic approaches.

The Evolution of Antibodies into Versatile Tumor-Targeting Agents

In recent years, monoclonal antibodies have become important weapons in the arsenal of anticancer drugs, and in select cases are now the drugs of choice due to their favorable toxicity profiles. Originally developed to confer passive immunity against tumor-specific antigens, clinical uses of monoclonal antibodies are expanding to include growth factor sequestration, signal transduction modulation, and tumor-specific drug delivery. In this review, we shall present the origins of antibody therapeutics within the field of immunotherapy and their evolution into effective anticancer agents, then discuss their multiple mechanisms of action, the basis of their tumor selectivity, and their therapeutic properties compared with traditional therapies. Antibodies are complex molecules whose efficacy and toxicity depend on the antigen, the antibody, any conjugated groups, and even the patient. Finally, we shall present new technologies being developed to increase the efficacy and selectivity of antibody-based therapeutics. Interestingly, many of the new approaches straddle the middle ground between immunotherapy and the traditional modalities of chemotherapy and radiotherapy, and can be seen as ways of combining the selectivity of the former with the efficacy of the latter.

Interrelations of clinicopathological variables, local immune response and prognosis in esophageal squamous cell carcinoma

The purpose of this study was to investigate the relationship between the local immune response, clinicopathological variables and prognosis in esophageal squamous cell carcinoma (SCC). A total of 377 cases of esophageal SCC without preoperative radiotherapy, chemotherapy or immunotherapy were studied. Corrected 5-year survival for pronounced, moderate and sparse immunocyte infiltration was 66%, 43% and 24%, respectively. In multivariate survival analysis, the immunocyte infiltration was an independent prognostic factor for survival (p<0.001). A correlation was found between density of T-cell and macrophage infiltration, depth of tumor invasion and lymph node metastasis using immunohistochemical analysis of the expression of T-cell, B-cell and macrophage markers. The results indicate that the local immunocyte infiltration is a manifestation of the host defense against cancer. It is therefore reasonable to infer that the local immunocyte infiltration in and around the cancer stroma is an important factor in predicting the prognosis of patients with esophageal SCC.

Assay for prostate specific antigen (PSA): problems and possible solutions

The absolute tissue specificity of prostate specific antigen (PSA) allows the use of PSA test not only for detecting recurrence or metastasis at an early stage after radical prostatectomy but also for screening prostate cancer if combined with digital rectal examination. There is also a need to improve the current PSA test to better differentiate between prostate cancer and benign prostate hyperplasia (BPH). Because of these clinical applications, a much greater demand was placed on PSA test for extra sensitivity, accuracy, and precision even within the normal PSA concentration range. However, the current commercial assay kits for PSA do not provide correct PSA values. Many factors contributing to the problem include the specificity of the anti-PSA antibodies, the composition of the calibrator, the PSA values assigned to the calibrator, the PSA isoform used for anti-PSA antibody preparation, the test design, and the composition of the diluent. Most problems were derived from the failure of realizing earlier that the majority of the PSA exists in serum not as free PSA but as complexes with protease inhibitors. Other problems, such as constantly changing composition of various forms of PSA in serum specimens, and different clearance rates for various forms of PSA make almost impossible to develop an ideal assay for PSA. Therefore, we suggest that test should be designed for measuring PSA-ACT (PSA-alpha 1-antichymotrypsin) complex only. Changing the focus from the measurement of total PSA of various forms to the PSA-ACT complex alone may improve the differentiation between prostate cancer and BPH but may also simplify the selection of anti-PSA antibodies and the preparation of calibrator for the assay.

Liver fatty acid-binding protein: a marker for studying cellular differentiation in gut epithelial neoplasms

Human liver fatty acid binding protein is a 127 residue cytoplasmic protein synthesized in liver and in the intestinal epithelium. Previous studies of normal and transgenic mice indicated that the liver fatty acid-binding protein gene is a sensitive marker of enterocytic differentiation. This study shows the use of immunohistochemical methods to examine liver fatty acid-binding protein gene expression in normal human colonic epithelium, colonic villoglandular adenomas, nonmucinous and mucinous adenocarcinomas, and several types of noncolonic epithelial neoplasms. Cells containing liver fatty acid-binding protein were found in normal colonic epithelium, in two thirds of colorectal villoglandular adenomas and nonmucinous adenocarcinomas, and in one third of mucinous adenocarcinomas but not in noncolonic, nonhepatic carcinomas. All liver fatty acid-binding protein-positive colonic adenomas and adenocarcinomas contained patches of immunoreactive cells distributed among histologically identical patches of cells without liver fatty acid-binding protein immunoreactivity. This "mosaicism" was also found in metastases from liver fatty acid-binding protein-positive colonic adenocarcinomas. Immunostaining of these liver fatty acid-binding protein-positive tissues for carcinoembryonic antigen did not show a mosaic cellular pattern in its expression. These data suggest that within a given neoplasm, differences exist in the differentiation programs of monoclonally-derived, malignant colonic epithelial cells and that liver fatty acid-binding protein is a useful marker for operationally defining these subpopulations. Liver fatty acid-binding protein is also a potentially useful diagnostic marker for colorectal and hepatic carcinomas.

Immunohistochemical demonstration of carcinoembryonic antigen (CEA) on tissue sections from squamous cell head and neck cancer and plasma CEA levels of the patients

45 squamous cell head and neck cancers including 36 with carcinoma of the oral cavity and 9 with carcinoma of the maxillary sinus were examined immunohistochemically for the presence of CEA. 12 of 30 carcinomas of the oral cavity and 7 of the 9 carcinomas of the maxillary sinus had tumors containing CEA. This difference in the occurrence of CEA was statistically significant. The mean plasma CEA level of 36 patients with carcinoma of the oral cavity and 7 patients with carcinoma of the maxillary sinus was 1.95 +/- 1.72 ng/ml and 3.70 +/- 3.53 ng/ml, respectively. Significant elevation of plasma CEA levels was found only in the stage-IV group patients with carcinoma of the oral cavity as compared with the stage-I group patients. In the 3 patients having plasma CEA values exceeding 5 ng/ml at the time of pretherapy, plasma CEA levels were decreased to below 2.5 ng/ml with the cancer treatment followed by the complete remission. These findings indicate that plasma CEA as a tumor marker in squamous cell head and neck cancer is meaningful in a small proportion of the cancer patient population.

Tumor markers: value and limitations in the management of cancer patients

Sixteen tumor markers are reviewed, and measured to the ideal: produced by the tumor cell alone absent in health and in benign disease present in all patients with a given malignancy level in the blood representative of tumor mass detectable in occult disease. The only marker that approaches the ideal is human chorionic gonadotropin (HCG) in gestational trophoblastic tumors. In this malignancy, the HCG level suggests the diagnosis and stage, confirms response to therapy, and predicts relapse. The three most widely used and intensely studied tumor markers are carcinoembryonic antigen (CEA), alphafetoprotein (AFP), and HCG. CEA cannot be used in screening for cancer, but in carcinoma of the colon its elevation preoperatively increases the likelihood of advanced disease and postoperative recurrence. Postoperatively, elevated titers are often but not invariably associated with recurrent disease. AFP and HCG are useful in the management of nonseminomatous germ cell testicular tumors. Like CEA, they cannot be used for screening. They are more likely to be increased with advancing stage, and after therapy rising levels almost always mean recurrent disease. Some markers are valuable in specific circumstances, such as calcitonin in screening for familial medullary carcinoma of the thyroid. In multiple myeloma, immunoglobulins are useful in determining the tumor mass and response to therapy. In neuroblastoma, catecholamine metabolites are useful primarily in making the diagnosis. In some malignancies, the absence of effective therapy lowers the value of the marker, as for AFP in hepatoma. The remaining markers are too unreliable or too little studied to be useful in the management of an individual patient with cancer. The purpose of this paper is to provide the clinician with an understanding of the limitations of the present tumor markers that will lead to wiser use of the tests, and to provide standards to which future tumor markers should be measured.

Immunohistochemical study of carcinoembryonic antigen in patients with colorectal cancer. Correlation with plasma carcinoembryonic antigen levels

Using peroxidase-antiperoxidase (PAP) method, carcinoembryonic antigen (CEA) was demonstrated in conventionally processed colorectal cancer tissues. A new immunohistochemical grading for colorectal cancers based on the mode of the localization was made in an attempt to clarify the factors responsible for elevation of plasma CEA levels in colorectal cancer patients. Most of the patients with well differentiated adenocarcinoma, in which CEA was densely distributed along the apical surface but only rarely present along the basolateral surfaces of the carcinoma cells, had very low levels of plasma CEA, whereas all patients showing CEA distribution in the stroma as well as over the entire surfaces of the cancer cells and their cytoplasm showed high plasma CEA levels. In addition, there was a good correlation between the grading and presence of the blood vessel and lymphatic invasions. Thus, the appearance of CEA in the surrounding stroma, due to abnormal distribution of CEA on the basolateral plasma membrane of cancer cells, may play a significant role in the elevation of plasma CEA levels in colorectal cancer patients.

Immunological studies of patients with tumours of the prostate and bladder (a retrospective analysis)

A total of 25 patients with bladder tumour and 35 with prostatic tumour were tested for humoral and cellular immune responsiveness in 1977. Information on the subsequent course of disease was collected 5 years later and confronted with the results of these tests. The most marked deviations in the values of acute-phase proteins, complement and lymphocyte transformation tests were found in those patients who had died within the first year of the investigations. The results approached or attained the normal values parallel with the survival times. The parameters studied thus seem to lend themselves to diagnostic and monitoring purposes.

Immunocytochemical detection of carcinoembryonic antigen in salivary gland tumors

The immunoperoxidase method was applied for carcinoembryonic antigen (CEA) detection in biopsy specimens of salivary gland tumors. 9 out of 10 adenoidcystic carcinomas revealed a strong and abundant reaction in tumoral glands. 10 other specimens of pleomorphic adenomas showed weak staining in the areas of epithelial proliferation. Normal glands adjacent to the tumor mass revealed a weak but constant reaction on the luminal border. As in other types of gland tumor, the quantitative estimation of CEA production by salivary gland tumors may be useful in the monitoring of recurrencies.

The immunohistological demonstration of carcinoembryonic antigen in intra-epithelial and invasive squamous carcinoma of the cervix

Using the sensitive peroxidase, anti-peroxidase immunohistological technique, carcinoembryonic antigen (CEA) was studied in formalin-fixed, paraffin-embedded cervical specimens from 225 patients. CEA was demonstrated in 33% of moderate dysplasia, 78.5% of severe dysplasia, 79% of in-situ carcinoma and 78% of invasive carcinoma. CEA was not demonstrated in normal squamous epithelium, squamous metaplasia, reserve cell hyperplasia nor in mild dysplasia.

Carcinoembryonic antigen detection by immunocytochemical methods in carcinomas of the colon and stomach

CEA was studied in paraffin sections from 50 cases of colonic and 50 cases of gastric adenocarcinoma using immunoperoxidase and immunofluorescence techniques. CEA was positive more frequently in colonic (86 per cent) than in stomach carcinoma (76 per cent). Immunoperoxidase was found to be the more sensitive technique for the detection of CEA in both organs. The non-neoplastic peritumoral colonic mucosa was more often CEA positive than was the peritumoral gastric mucosa. CEA was found more often, and the intensity of the staining was stronger in well-differentiated colonic and gastric carcinoma than it was in poorly differentiated carcinoma. No relation was found between the presence of CEA in colonic and gastric carcinoma and the stages of the disease. CEA was detected more frequently in carcinomas of the left colon than in carcinomas of the right colon.

Alpha-fetoprotein: cellular origin of a biological marker in rat liver under various experimental conditions

Alpha1-fetoprotein (AFP) was detected by serological, light and electron microscopic methods in various experimental models. These included (a) liver regeneration after partial hepatectomy or CCl4 intoxication (mouse and rat); (b) liver intoxication by high doses of N-nitrosomorpholine (NNM) and chemical induction of hepatomas (rat). AFP levels varied greatly according to the animal species and strains used. Low and high AFP-producing species and strains were distinguished. In liver regeneration after hepatectomy or CCl4 intoxication, cellular AFP was found in the cytoplasm of hepatocytes. In NNM-intoxicated livers, elevated AFP levels were associated with proliferation of canalicular epithelial cells in which AFP was localized. In early stages of hepatocarcinogenesis, significant AFP increase occurred after high-dose carcinogen feeding and AFP was also localized in proliferating canalicular epithelial cells. On low-dose NNM feeding, no cellular AFP was detected unless hepatomas had developed. At the stage of malignant conversion, distinct AFP staining and non-AFP staining hepatocellular carcinomas appeared in livers.

The presence and distribution of carcinoembryonic antigen in tumors of human minor salivary glands

Using an immunoperoxidase method we have demonstrated carcinoembryonic antigen (CEA) in more than half of a series of 62 tumors of minor salivary glands. CEA was present in both benign and malignant tumors. Its presence was related mainly to the formation of well differentiated ductal tissue in the neoplasms rather than to the histologic type of tumor. Although of only limited diagnostic value, the histologic presence of CEA in a particular tumor may indicate the possibility of postoperative monitoring of saliva and plasma, particularly where residual tumor, metastases or recurrences are considered likely.

Biologic markers in cancer diagnosis and treatment

We have reviewed several tumor markers that our advocates feel are now clinically useful, involve current assay technology, and are based on already available information. These include, in selected instances, estrogen receptors for breast cancer, thyrocalcitonin for medullary cancer of the thyroid, prostatic acid phosphatase for cancer of the prostate, alpha-fetoprotein for hepatocellular cancer, and carcinoembryonic antigen for monitoring colon cancer. We have considered the potential use of measurement of serum proteases and protein degradation products due to their activity as possible future areas of development, and we have explored measurement of tissue aryl hydrocarbon hydroxylase to identify populations at risk of cancer resulting from chemical carcinogenesis. It is clear that the study of tumor markers is already improving patient care in some specific areas and offers exciting potential for the future.

Immunologic aspects of gynecologic cancer

All vertebrates have a defense mechanism, the immune defense system, that protects them from disease-causing microorganisms. Its deliberate exploitation has conquered many infectious diseases and has been a major achievement of medical science in preventing suffering and saving lives. At the beginning of this century, hope was held that dissimilarities between normal and neoplastic cells could be demonstrated by immunologic methods and that vaccination against cancer might become possible. When it was recognized that the many claims of tumor=specific antigenicity were based on experiments in which an immunity to normal alloantigens, rather than tumor-specific antigens, had been demonstrated, the field of tumor immunology came into disrepute. The work of Gross in 1943 and Prehn and Main in 1957 rekindled interest in tumor immunology. Many contributions have advanced the concept of tumor immunology. They are the following: (1) an abundant supply of highly inbred (syngeneic) animals; (2) extensive work on experimental transplantable tumors; (3) an understanding of the mechanism causing rejection of grafted normal and cancerous tissues in animals; (4) identification of the function of the humoral and cell-mediated mechanisms following organ transplantation; (5) the observation that cancers do arouse a specific immune response in the organisms in which they appear; (6) antigenic differences represent the first known qualitative distinction between cancer cells and their normal counterparts; (7) the application of improved technology--columns, use of fluorescein-tagged antibodies, urea as a chaotropic agent, nephelometer; (8) hybridoma to produce a supply of monoclonal antibodies; (9) new vaccines directed against invasive tumors, and (10) the exploration of the role of immune complexes in oncology. The areas of promise and the future of cancer immunology have once again challenged the minds of scientists.

Comparison of serum beta 2-microglobulin and carcinoembryonic antigen (CEA) in the follow-up of breast cancer patients

Using commercially available radioimmune test kits, serial determinations of serum beta 2-microglobulin and CEA were performed in 337 patients, who had been treated for breast cancer by modified radical mastectomy and radiotherapy. The pre-therapeutic data indicated a higher incidence of pathological beta 2-microglobulin and CEA levels in patients with distant metastases than in patients with localized disease. However, this finding did not allow the conclusion of a direct complementarity of beta 2-microglobulin and CEA as tumour markers, since the group of patients with distant metastasis contained a high percentage of elderly patients who generally can be expected to have elevated beta 2-microglobulin serum concentrations. Therefore, the correlation of the clinical course of malignant disease and the incidence of relapses with the changes of serum beta 2-microglobulin and CEA concentrations was examined during the post-treatment surveillance: 7/9 cases (78%) with local recurrence and 46/73 cases (63%) with distant spread of disease were not indicated in the beta 2-microglobulin follow-up by pathologic serum concentrations, whereas in the CEA follow-up only 1/9 and 2/73 false negative indications were registered. The poor correlation suggests that serum beta 2-microglobulin is not directly tumour associated in breast cancer and does not fulfill the criteria of a tumour marker.

Antigen(s) expressed on cultured cells of various species that crossreact with tumor antigens(s)

Antibodies eluted from a methycholanthrene induced sarcoma (MC-D) of strain 13 guinea pigs were examined for reactivity against 11 cultured cell lines derived from unrelated tumors and 11 cell lines originating from normal tissues of various species by radioimmunoassay. Six tumor-derived lines of mouse, hamster, rat, guinea pig and man and five "normal" cell lines of guinea pig, human and fish origin showed significant reaction.

Radioimmunoassay for carcinoembryonic antigen and alpha 1-fetoprotein in the qualitative evaluation of focal hepatic lesions in Japan

The combined tests of serum alpha 1-fetoprotein (AFP) and carcinoembryonic antigen (CEA) were routinely performed in 210 patients with focal hepatic lesions on a 99mTc-colloid liver scan in order to determine whether these could provide more useful information that AFP test alone in the qualitative evaluation of focal hepatic lesions. The predictive value of hepatoma with positive AFP alone remained 80%. However, when the negative CEA was combined with positive AFP, the predictive value of hepatoma (91%) with both was greatly increased. On the other hand, the predictive value of metastatic liver cancer with positive CEA showed 92%. The combined test of AFP and CEA may be useful for preserving high predictive values of hepatoma and metastatic liver disease.

Products of gynaecological neoplasms: clinical and pathological applications

Alphafetoprotein is at present the only 'antigen' of proved clinical value in gynaecological neoplasia. Its synthesis and release by a particular type of germ cell tumour (yolk sac, endodermal sinus tumour) present alone or as part of a teratoma approaches many of the essential criteria of a utopian tumour marker. Unfortunately, none of the other recognised 'antigens' expressed and/or released by gynaecological tumours and which have been adequately assessed in the clinical situation, seem to represent laboratory adjuncts essential for adequate patient care at present. Further research is needed to define other factors if this approach to improving diagnosis and management is to succeed.

Correlation of histology and alpha 1-fetoprotein resurgence in rat liver regeneration after experimental injury by galactosamine

Intraperitoneal injections of galactosamine-HCl in rats were followed by transitory elevations of serum alpha-fetoprotein (AFP) concentrations. These were associated with regeneration of the damaged liver; a maximum of serum AFP was reached on day 4 (2.08 +/- 0.67 microgram/ml). In sera of untreated rats, serum AFP levels were less than 0.1 microgram/ml and no cellular AFP was detected in liver sections. Two days after galactosamine injections, AFP was localized for the first time in the cytoplasm of epithelial cells of bile ducts and canaliculi in portal spaces. The intensity of AFP staining reached a maximum between days 3 and 4. In addition, faint but distinct AFP-positive reactions were seen in the cytoplasm of randomly distributed hepatocytes. After day 5, AFP-staining cells rapidly disappeared. A strong correlation was noted between reappearance of AFP in sera, intensity of epithelial bile duct proliferation and cellular AFP staining.

Identification and characterization of a brain-specific antigen enriched in neonatal brain. II. Antigenic stability, species cross-reactivity and tumor cell association

NABSA is a brain-specific antigen enriched in neonatal brain. Microcomplement fixation was used to determine the extent of serological stability of NABSA towards heat denaturation and freeze-thaw denaturation. NABSA antigenic activity was progressively lost from neonatal and adult brain solutions incubated at temperatures above 40 degrees C. All activity was lost above 65 degrees C. Dilute solutions of NABSA were stable at 8 degrees C for at least two weeks and could be frozen and thawed in Tris.phosphate buffer at concentrations above 2 mg/ml with little loss of activity. NABSA was found in every vertebrate species tested. An unusually close structural similarity (a frequent characteristic of both brain-specific antigens and fetal antigens) was demonstrated by serological methods among the mammalian and avian NABSAs. NABSA was detected by microcomplement fixation analysis in 4 out of 16 rat and murine neural clonal tumor cell lines. There was no clear limitation of NABSA to a particular class of neural cell (as defined by the phenotypes of these tumor cell classes) or to rapidly dividing or stationary phase cells. NABSA may be a brain-specific oncofetal antigen (OFA-associated), since it is present in tumor cells of the nervous system and high levels are found in immature brain.

Ferritin, a sensitizing substance in the leucocyte migration inhibition test in patients with malignant lymphoma

The nature of the factor in Hodgkin's disease involved spleen to which many patients with malignant lymphoma react in the leucocyte migration inhibition test has been investigated. Our results suggest that ferritin from Hodgkin's disease involved spleens is antigenically different to that prepared from normal spleen. Isoelectric focusing shows the presence of more acidic 'isoferritins' in ferritin prepared from Hodgkin's disease involved spleen than in that prepared from normal spleen. Further observations using the leucocyte migration inhibition test suggest that sensitization to the abnormal ferritin, acting as an onco-fetal tumour associated substance, may be responsible for the reaction of patients with malignant lymphoma in this test.

Demonstration of chicken fetal antigen (CFA) on normal splenic lymphocytes, Marek's disease lymphoblastoid cell lines and other neoplasms

Chicken fetal antigen (CFA) was detected on normal splenic lymphocytes and a direct relationship was observed between the percentage of CFA-positive cells and the age of the donor. The fetal antigen was also detected on lymphoblastoid tumor cells and cell lines induced by known avian oncogenic viruses (Marek's disease virus and avian leukosis virus), and on spontaneously occurring adenocarcinoma cells. The fetal antigen appears to be distinct from Marek's disease tumor-associated surface antigen.

The early effects of chemical carcinogens on adult rat hepatocytes in primary culture. II. Effects on unscheduled DNA synthesis, cell division and alpha-fetoprotein production

The effects of exposure of rat hepatocytes in primary maintenance culture to chemical carcinogens has been studied with respect cytotoxicity and alterations in mitotic index, unscheduled DNA synthesis and alpha-fetoprotein (AFP) production. All compounds tested produced cytotoxicity. Increases in mitotic index and unscheduled DNA synthesis and the production of AFP were observed after treatment of the cells with the carcinogens but not after treatment with the non-carcinogenic isomers. These increases were dose-dependent and depended on the time of exposure and the time incubated postexposure. The patterns of the increase in mitotic index and AFP production after cessation of carcinogen exposure were very similar, with the increase in mitotic index occurring slightly before that for the AFP production and it is suggested from this and other data that the production of AFP is dependent on the generation of a cell species functionally distinct from the non-dividing hepatocytes. It is also suggested that measurement of unscheduled DNA synthesis in conjunction with that of AFP production in cultured hepatocytes may be useful as part of a screening programme for chemical carcinogens.

Pathology of primary liver cancer

After a brief survey of the factors that play a role in the etiopathogenesis of human hepatocellular carcinomas, a detailed description is given of the macroscopic and microscopic features of human liver cancers as well as their association with cirrhosis. The ultrastructural features of liver cancers of various degrees of differentiation are described. The mode of spread, metastasis formation of primary liver cancers, and most frequent causes of death of liver cancer patients are reviewed.

Expression of an onco-developmental antegen among avian species

Rabbit antisera directed against an onco-developmental antigen on chicken red blood cells have been serologically dissected through specific adsorptions. It is now possible to detect 13 antigenic determinants with the fractionated antisera. The onco-developmental antigen referred to as chicken fetal-leukemic antigen (CFA) is fetal-specific in the white Leghorn chicken, being present on the embryonic but not adult peripheral red blood cells of non-being present on the embryonic but not adult peripheral red blood cells of non-leukemic birds. However, one or more of the onco-developmental antigenic determinants have been detected on adult peripheral red blood cells of non-Gallus avian species, as well as on red blood cells from two adult chicken varieties. For phylogenetic purposes, red blood cells from avian species were characterized for their combinations of CFA determinants. Comparisons among species revealed specific patterns of antigenic expression within phylogenetic groups. Several CFA determinants were restricted in their occurrence to species within a single family, and one determinant was found in all cases where CFA was expressed. The distribution of CFA determinants was used to determine immunological distances among four Galliform species. These distances agreed with the immunological relationships established using different serological markers.

Use of CEA as an indicator of early recurrence and as a guide to a selected second-look procedure in patients with colorectal cancer

The usefulness of the CEA as an indicator of recurrence and a guide to selected second-look surgery was evaluated from a retrospective analysis of 358 patients with colorectal cancer and from a prospective experience with 16 patients all of whom had been admitted for second-look surgery because of postoperative elevations of CEA only. Our previous experience had shown that after curative resection the CEA usually returned to normal levels (less than 5 ng/ml) within one month, but became elevated at time of clinically obvious recurrence being very high in patients with liver metastases, but only moderately elevated or normal in patients with local recurrence. All 16 patients had previously had curative resection of colorectal cancer; 13 in the rectum or rectosigmoid and three in the right colon. There were 13 Dukes' C and three Dukes' B cancers. All had been followed clinically and by CEA testing at three monthly intervals and were considered free of disease (NED) at time of CEA elevation. The median disease free interval was 13 months (range 4-57 months) and the median CEA prompting admission for second-look operation was 21 ng/ml (range 10-56 ng/ml). The sites of recurrence were liver in six, lung in two and localized disease in six. Two patients had negative exploration for recurrence and were found to have cholelithiasis only (one of these later died of metastases). Resection for cure was done in seven and palliative resection or biopsy only was done in nine patients. At this time, four patients are NED (12-37 months), five are living with disease (10-16 months) and seven have died of disease (2-12 months). The CEA test provides a method of early detection of recurrence and may permit surgical retrieval in selected patients and earlier initiation of palliation in other patients. The longterm effects in patient salvage remain to be defined.

Evaluation of a direct radioimmunoassay for carcinoembryonic antigen

1. A radioimmunoassay for CEA using commercially available reagents (CEA-Roche), which avoids the perchloric acid and dialysis steps used in the CEA-Roche assay, has been devised. 2. Comparison of results on 746 plasma samples using our assay with those obtained using the CEA-Roche assay revealed a highly significant correlation coefficient (0.72; p less than 0.00001). 3. A further comparison of results on 373 plasma samples using our assay, but including a preincubation step with goat serum, with those obtained using the CEA-Roche assay also revealed a highly significant correlation coefficient (0.89; 0.00001). The goat serum preincubation step eliminated most of the discordant results in which our assay value was higher than CEA-Roche assay, presumably because of anti-goat antibodies in the patient plasma sample.

Identification and characterization of a brain-specific antigen enriched in neonatal brain. I. Developmental, regional distribution and molecular weight studies

An antiserum raised to the 20--40% ammonium sulfate cut of the soluble proteins extracted from whole neonatal rat brain has been absorbed with liver affinity columns. The absorbed antiserum recognizes a high molecular weight antigen(s) that is (i) restricted to nervous tissue, (ii) enriched in neonatal rat brain, and (iii) present from the 17th day of gestation throughout adult life. The name given to this brain-specific antigen(s) is NABSA, short for 'neonatal-associated brain-specific antigen'. NABSA is immunologically unrelated to S-100 or 14-3-2. NABSA levels in whole rat brain increased soon after birth. The specific activity of NABSA at 2--3 days postpartum reached 3--5-fold higher levels than are found in adult brain. NABSA declined to adult levels by the 10th postnatal day, well before CNS maturation was complete. Regional variations in NABSA levels were found in the rat neonate; highest activities occurred in neonatal cerebellum. Similar variations were observed in adult brain.

A correlation of serum C3DP levels with chemotherapeutic management of cancer patients

Serial serum C3DP levels of 33 patients at our institution have been followed for up to 10 months. Individuals experiencing periods free of symptoms and signs of proliferating or expanding malignant disease, had C3DP levels which remained below 150 microgram/ml. Patients with active or recurrent disease, while on chemotherapy, had elevated C3DP values (greater than 150 microgram/ml). Serum C3DP values declined abruptly following treatment which resulted in major reduction of tumor mass. Decreases in C3DP levels from values above 150 microgram/ml to values within the normal range (50-150 microgram/ml) were observed during 89% (25/28) of the favorable clinical responses which have been followed with C3DP assays. Increases in C3DP levels from values within the normal range to values above 150 microgram/ml were observed either prior to or coordinate with clinical symptoms of disease recurrence 83% of the time (10/12 cases). These studies suggest that serial C3DP determinations offer an excellent prognostic aid for evaluating the response of malignant tumors during chemotherapeutic management.

Serum biochemical markers in lung cancer

The prevalence of elevated serum levels of 5 potential tumour-associated antigens was determined in patients with lung cancer sampled at the time of initial presentation, using age- and sex-matched patients with benign lung disease as controls. Elevated levels (greater than upper 95th centile of controls) were found as follows: carcinoembryonic antigen (CEA), 17%; pregnancy-associated alpha-macroglobulin (PAM), 16%; casein 14%; human chorionic gonadotrophin (HCG) 6%; alpha-foetoprotein (AFP), 1.5%. The prevalence of elevated CEA levels (but not other markers) was higher in patients with evidence of extra-thoracic tumour spread (23%) mainly due to anaplastic tumours and adenocarcinomas. A degree of concordance of elevated marker levels occurred with CEA, HCG, casein and AFP, but there was a striking discordance of elevated CEA and PAM levels. Simultaneous assays of CEA and PAM will detect the majority of patients with elevations of any of the markers studied, and are likely to be the most useful biochemical markers in following the response of lung tumours to therapy.