Differences in expression of SPan-1 and CA15-3 antigens in blood and tissues.

Pancreatic and mammary cancer cells are reported to have different oligosaccharides on the same apomucin, the MUCI gene product. A better understanding of the tissue specificity of these sugar structures may help in identifying the source of mucins when they are found in the sera. Serum levels of 3 pancreatic-cancer-associated carbohydrate epitopes identified by monoclonal antibodies (MAbs) SPan-1, 19-9 and DU-PAN-2, were compared to those of CA15-3 in a variety of malignant conditions. CA15-3 identifies both carbohydrate and peptide determinants associated with the MUC1 apomucin in breast tissues. SPan-1 antigen was elevated in a high percentage of patients with pancreatic, gastric and colorectal cancer but in only a few of the patients with malignancies of non-GI origin such as breast, ovary and lung. The 19-9 and DU-PAN-2 antigens had a similar pattern of much greater sensitivity for pancreatic cancer than for these non-gastrointestinal cancers. The levels of these 3 markers showed significant correlations in pancreatic cancer. In contrast, CA15-3 was elevated in a large number of patients with breast, lung, ovarian and pancreatic cancers. There was no correlation of CA15-3 with the 3 other markers in pancreatic cancer. SPan-1 and DF3/115D8 antigens in blood have different mobilities in SDS-PAGE and buoyant densities. Moreover, SPan-1 and DF3 antigenic determinants are localized in different regions of the same normal and malignant pancreas and breast tissues. Thus the SPan-1 determinant can be dissociated from the breast peptide and/or carbohydrate determinants.     

Antibodies to mouse mammary tumor virus-related antigen in sera of patients with breast carcinoma

Sera from patients with breast carcinoma, benign breast disease, malignancies other than breast carcinoma, and healthy female controls were analyzed by indirect immunofluorescence for the presence of antibodies directed toward antigens of mouse mammary tumor. Sera from 56 to 137 (40.9%) patients with breast carcinoma were positive. Positive reactivity was also found in sera from 5 to 27 (18.5%) patients with benign breast disease, in 7 of 60 (11.7%) patients with malignancies other than breast carcinoma, and in 2 of 56 (3.6%) female controls. In the group of patients with breast carcinoma a correlation was noted between age and the probability of detection of these antibodies. Histopathologic examination of breast cancers indicated that antibodies to antigens in mouse mammary tumors were more often found in patients with infiltrating ductal carcinoma of the mucinous type than with other types of breast tumors. No correlation was demonstrable between the incidence of detection of these antibodies and the stage of the disease. Immunochemical analyses indicated that the antibody activity was present in IgG and IgM classes of immunoglobulins. The human antibodies to antigens in mouse mammary tumors could be removed from patients' sera by absorption with disrupted mouse mammary tumor virus (MMTV) but not with gp52 or gp34 (52,000 and 34,000 dalton polypeptides) of MMTV, or with Rauscher mouse leukemia virus (MLV).     

Identification of breast cancer-restricted antigens by antibody screening of SKBR3 cDNA library using a preselected patient's serum

Screening of a breast cancer cDNA library from SKBR3 human breast cancer cells by SEREX (serological analysis of cDNA expression library) using a preselected serum from a breast cancer patient revealed 13 genes, two of which, INT-MI-1 and INT-MI-2, encode novel gene products, while the remaining 11 genes and their products are identical with or highly homologous to known GenBank entries. Immunoscreening of the 13 clones using 20 allogeneic sera from breast cancer patients and 20 samples from age- and gender-matched healthy donors showed that lactate dehydrogenase-A (LDH-A), lactate dehydrogenase-B (LDH-B), fibulin-1, and thyroid hormone-binding protein (THBP) were recognized principally by the breast cancer patient sera, indicating the immunogenicity of these molecules in vivo. The other antigens were similarly recognized by normal and patients sera, and thus not tumor-restricted immunologically. RT-PCR analysis revealed strong expression of fibulin-1 in tumor cell lines and surgical specimen whereas in the same experimental conditions, normal tissues scored negative. Also THBP expression was found in various tumors whereas in normal tissues, its expression is restricted to the testis and, at lower levels, in ovary, liver, and spleen. In contrast, LDH-A and LDH-B were ubiquitously expressed in normal and tumor tissues, with LDH-B levels considerably lower and heterogeneous in normal samples compared to those expressed in tumor cell lines. The differential expression of fibulin-1 between the normal tissues and breast carcinoma cell lines (5/6) and surgical specimens (5/6) suggests the possible involvement of the overexpression of this extracellular matrix-associated glycoprotein in the pathogenesis of this neoplasm.     

Generation and immunohistological characterization of human monoclonal antibodies to mammary carcinoma cells

The purpose of this study was to identify human antibodies generated against autologous breast tumor cells by the host's immune response. Accordingly, lymphocytes from lymph nodes of seven different patients with metastatic breast carcinomas were immortalized by fusing them with a nonsecreting variant of murine myeloma cells. The screening for binding of antibodies to tumor cells was performed by indirect immunoperoxidase staining of paraffin-embedded tissue sections of the autologous tumor. The selected hybrid cells, after being cloned three times, were stable for the secretion of immunoglobulins for over 2 years. A total of 81 human immunoglobulin-producing clones was obtained from an initial 595 wells with hybrid growth. Nine of these clones produced immunoglobulin M, none of which showed detectable binding to tissue antigens in breast. Seventy-two clones produced immunoglobulin G monoclonal antibodies, and 15 of these showed preferential binding to breast carcinoma cells. Three of these immunoglobulin G monoclonal antibodies were subjected to detailed immunohistological evaluations. Using these antibodies at concentrations ranging from 10 to 100 ng/tissue section, the morphologically normal mammary epithelial cells could be discriminated from their malignant counterparts. The antibodies showed diffuse staining of cytoplasmic components in the malignant counterparts. Under these conditions, lymphocytes, erythrocytes, and stromal cells in breast tissues were unstained. The antibodies showed variable reactivity with malignant epithelial cells of colon and stomach, and with normal epithelial cells lining the renal tubules and sebaceous glands in skin. Antigenic heterogeneity of malignant mammary epithelial cells was revealed. The antibodies may have value in the characterization of tumor-associated antigens responsible for inducing autologous immune responses.     

Elevated levels of a high molecular weight antigen detected by antibody W1 in sera from breast cancer patients

A novel screening assay was used to test 13 previously described antibreast cancer antibodies for those which recognize antigens elevated in serum of breast cancer patients. Binding of three of these antibodies to breast or lung carcinoma cells was inhibited to a significantly greater extent by tumor patient serum than by normal serum, suggesting that the antigens might be useful serum markers. Two of these antibodies, W1 and W9, were shown to recognize nonoverlapping epitopes on a high molecular weight molecule(s) purified from serum from breast cancer patients. A sensitive double determinant immunoassay was developed to measure W1 antigen levels in sera from a total of 389 cancer patients and controls. Forty seven % (37 of 79) of individuals having breast cancer showed elevated serum levels of the W1 antigen, whereas only 4% (1 of 25) of normal controls and 2% (1 of 47) of patients hospitalized for nonmalignant disorders showed elevated levels. These differences were statistically significant (P less than 0.001). The percentage of breast cancer patients showing elevated serum levels was greater for individuals with metastatic disease. Statistically significant numbers of lung, ovarian, and prostate, but not colon, cancer patients also had elevated serum levels of the W1 antigen. These data suggest that measurement of the W1 antigen in serum might provide clinically useful information on the course of metastatic breast and other cancers.     

Two monoclonal antibodies selective for human mammary carcinoma

Mouse myeloma cells were fused with spleen cells from BALB/c mice immunized with the MCF-7 human mammary carcinoma cell line. Among hybridomas, two (3B18 and 15A8) were selected and cloned. Hybridoma 3B18 produces kappa-IgG1 antibodies that react with a cytoplasmic component of MCF-7 cells. In immunoperoxidase assays, 3B18 reacts with 27 of 31 specimens of human mammary carcinoma. It reacts most consistently with poorly differentiated and infiltrating ductal breast cancers, but it also reacts with isolated cells in 3 of 5 benign mammary pathological lesions with a variable distribution. The antibody does not react with normal mammary epithelium. It does not react with any normal human tissues, and it reacts with only one of 19 other cancers tested. Hybridoma 15A8 produces kappa-IgG1 antibodies that react with the surface membranes of the cells of two human breast cancer cell lines but not with a human fibroblast cell line. In immunoperoxidase assays, the antibody reacted with 28 out of 31 human mammary carcinomas. The antibody also reacts more weakly with normal human epithelial cells of breast, renal proximal tubule, skin, esophagus, and salivary gland, but no other normal tissue. The antibody was unreactive with 14 of 18 other malignant tissues tested. Since 3B18 and 15A8 detect antigens found predominantly in human mammary carcinomas and, possibly, distinguish overlapping categories of human mammary carcinomas, they may prove useful in determining the cellular lineage from which human mammary carcinomas arise, or they may have other clinical applications in breast cancer.     

Antibody reacting with the murine mammary tumor virus in the serum of patients with breast carcinoma: a possible serological detection method for breast carcinoma

Sera from patients with Stages A and B infiltrating ductal carcinoma of the breast, benign breast disease, cancers other than breast carcinoma, and normal female controls were examined by indirect immunoelectron microscopy (IEM) and a viral agglutination test for evidence of antibodies directed against murine mammary tumor virus (MMTV). Sera from 41 (79%) of 52 patients with breast carcinoma and eight (19%) of 42 normal subjects or patients with benign breast disease (noncancer subjects) showed evidence of MMTV labeling by IEM. In the MMTV agglutination test, significant virus agglutination (2+ to 4+) was present in eight (13%) of 61 noncancer sera, 58 (86%) of 68 breast carcinoma sera, and two (11%) of 18 other cancer sera. The results of the more rapid MMTV agglutination test correlated well with IEM. Analysis of reacting antibody by IEM revealed no immunoglobulin A and significant immunoglobulin M and immunoglobulin G antibody. Serum reactivity against MMTV was completely absorbed by MMTV but not by the glycoprotein with a molecular weight of 52,000 of MMTV, Friend murine leukemia virus, avian myeloblastosis virus, or sheep erythrocytes. It is concluded that reactivity of human antibodies to MMTV is strongly associated with, but is not entirely specific for, breast carcinoma. It remains to be determined if normal persons with these antibodies will ultimately develop breast cancer and should therefore be considered at high risk. These tests may have potential usefulness as a diagnostic screen for breast cancer.     

Presence of breast cancer antigens in uninvolved axillary lymph nodes

Monoclonal antibodies which bind to breast cancer have been used to evaluate the detection of metastatic disease in axillary lymph nodes. Three monoclonal antibodies (H59, H71, and H72) were reacted with tissue sections of primary tumors and axillary nodes from 24 mastectomy specimens and four specimens from glandular mastectomies for benign disease. All three antibodies had been shown to react with subsets of normal and malignant breast tissue; did not bind erythroid, myeloid, or lymphoid tissue; and recognized antigens in paraffin-embedded tissue. The antibodies recognized cell surface antigens, and H59 and H72 bound to glycoproteins which are either sloughed or secreted. Primary tumors and tumors in lymph nodes from the same specimen were always bound by the same antibodies. Antibodies detected unrecognized microscopic tumor in nodes from one previously node-negative specimen and two specimens with positive nodes. This suggests that monoclonal antibodies may be useful for detecting metastatic breast cancer in nodes which by light microscopy are negative. Moderate binding of H59 and H72 antibodies to sinus histiocytes and perivascular cells was observed in all uninvolved nodes with sinus hyperplasia obtained from benign and malignant specimens. Thus, breast antigens can be identified in hyperplastic nodes in patients with no evidence of breast cancer. The antigens are detected predominately in the lymphoid sinuses and are bound to nonneoplastic cells. Therefore, breast antigens are regularly being processed and presented by normal lymphoid cells within the sinus. The binding of these monoclonal antibodies to axillary lymph nodes does not necessarily indicate the presence of metastatic disease. Dense binding to paracortical single cells was observed in tumor-containing lymph nodes and in uninvolved nodes obtained from mastectomy specimens with breast cancer. These cells are infrequent, and their number in an uninvolved node correlates with the pathological stage. They represent either binding to isolated lymphoid cells or metastatic tumor. Studies are under way to determine the origin of these cells.     

Generation of monoclonal antibodies against human lung squamous cell carcinoma and adenocarcinoma using mice rendered tolerant to normal human lung

Four murine monoclonal antibodies against human lung carcinoma were generated using a novel immunization procedure. BALB/c mice were rendered neonatally tolerant to normal human lung tissues and subsequently immunized with human lung tumor tissues. The lower level of antibody-reactivity to the tolerogen was seen in the sera of mice rendered neonatally tolerant as compared with the level of reactivity in the sera of nontolerant mice. The mice which maintained a sufficiently tolerant state were selected for hybridoma production. Two monoclonal antibodies, KM-32 and KM-34, were developed from mice immunized with lung squamous cell carcinoma tissues and two other monoclonal antibodies, KM-52 and KM-93, were developed from mice immunized with lung adenocarcinoma tissues. Distribution of antigens detected by the monoclonal antibodies were investigated by enzyme-linked immunosorbent assay using membrane fractions prepared from a number of tumorous and normal tissues and various human normal and tumor cell lines. KM-32 recognized a carbohydrate antigen expressed predominantly on lung squamous cell carcinoma cells and its carbohydrate structure appeared to be associated with blood group A antigen. KM-93 recognized a sialylated carbohydrate epitope on the antigen expressed on lung adeno-carcinoma cells and a few other tumor cells. KM-34 and KM-52 detected protein or glycoprotein antigens and they showed predominant reactivity to lung squamous cell carcinoma and lung adenocarcinoma, respectively. KM-32 and KM-34 antibodies showed complement-dependent cytotoxicity against a lung tumor cell line. These results suggest that the tolerance technique is useful for efficient screening of murine monoclonal antibodies specific to human tumors. The efficacy of these four monoclonal antibodies in diagnosis and therapy of lung cancer will be the subject of a sequential study.     

Biochemical and immunological characterizations of antigens recognised by human monoclonal antibodies

The lymphocytes from lymph nodes of six patients with metastatic mammary carcinomas were hybridised by fusion with a non-secreting variant of murine myeloma cells. Hybrid cells producing human immunoglobulin were detected by screening of culture supernatants using a solid-phase enzyme-linked immunosorbent assay for human IgG or IgM. Reactivity of human immunoglobulins to breast tumour cells was assessed by an indirect immunoperoxidase staining of fresh-frozen breast carcinoma sections. In the initial screening, the tissues used were those removed from the patients who acted as source of lymphocytes for fusion. The hybrid-cells, after repeated cloning, were stable for secretion of immunoglobulins. A total of 14 immunoglobulin G and 51 immunoglobulin M human monoclonal antibodies, showing variable reactivity to mammary carcinoma cells in tissue sections by an indirect immunoperoxidase staining method, were obtained. Two immunoglobulin G monoclonal antibodies (designated HMA-29 and HMA-31) were selected on the basis of their strong reactivity to the tumour cells and utilised to identify their corresponding antigens. The antibodies quantitatively discriminated, as expressed by the degree of staining, malignant from normal or benign mammary epithelia in freshly frozen or formalin-fixed breast tissues. The antibodies also showed reactivity to malignant cells of colon, stomach and lung and to normal cells lining the renal tubules and surface epithelium of colon. As revealed by blocking experiments, the epitopes recognised by these antibodies were not expressed on carcinoembryonic antigens, erythrocytes, lymphocytes, glycoproteins from milk-fat-globule membrane or keratins. The antibody HMA-29 immunoprecipitated a phosphoprotein (Mr = 29,000), and antibody HMA-31 two protein components (Mr = 31,000 and 34,000), from lysates of intrinsically labelled human mammary carcinoma cell line (MCF7). Neither of these proteins were present in detectable amounts in an intrinsically labelled melanoma cell line. Immunoblocking and immunoprecipitation experiments suggested that epitopes recognised by these two antibodies are dissimilar and are expressed on different molecules. The antibodies appear to be useful for functional characterisation of those antigens which are present in elevated levels in malignant compared with normal mammary epithelia.     

Monoclonal antibodies against carcinoma cells of the human urinary bladder: immunohistochemical staining of tissues

We have previously described the generation of mouse monoclonal antibodies (Mabs) directed to cell surface antigens of human bladder carcinoma. Based on experiments with cultured cells and a limited number of freshly isolated tissues, four distinct antigens were identified as being associated with this disease. In the present investigation, comprising the immunostaining of tissues of normal, malignant, and fetal origin, we have confirmed and extended the close association of these antigens with bladder cancer. Antibodies to all four antigens could clearly discriminate between malignant and normal uroepithelium. Two of the antibodies, SK4H-12 and 4E8, showed no additional reaction when tested with various adult tissues of normal or malignant origin. Antibodies to the remaining two antigens gave a positive staining of a few other tissue types.     

Testing for anti-p53 antibodies increases the diagnostic sensitivity of conventional tumor markers

The aim of this study was to determine whether anti-p53 antibodies are of clinical significance as a serological marker in the diagnosis and monitoring of malignancies. A total of 1874 serum samples from 591 patients with various types of cancer, esophageal, gastric, colorectal, pancreatic, hepatocellular, breast, and urogenital cancer, and 436 control individuals were analyzed by immunoblot for antibodies against p53. The anti-p53 antibody test was correlated with expression of conventional tumor markers, survival and the clinicopathological features of malignant disease. Anti-p53 antibodies were found in 23.4% (138/591) of the sera of patients with malignant disease (range 11.5-34%). The detection of anti-p53 serum antibodies had a specificity of 100% for malignancy (p<0.0001). The overall sensitivity of measuring established tumor markers was 62.9% (372/591). The elevation of conventional tumor markers and the presence of anti-p53 antibodies in the sera of patients with malignant disease turned out to be an independent variable (p<0.05). Combination of established tumor markers with the anti-p53 antibody test led to an increase in diagnostic sensitivity of 8% (49/591) (p<0.01). Thus, the independence of anti-p53 antibodies from established tumor markers allows the serological detection of additional tumor patients. Kaplan-Meier analysis revealed a trend toward a poorer prognosis in hepatocellular carcinoma and breast cancer patients who were anti-p53 serum positive. In conclusion, testing for anti-p53 antibodies can increase the diagnostic sensitivity when used in combination with measurement of conventional tumor markers. This increase is achieved without a parallel decrease in specificity.     

A radioimmunoassay for the detection of a human tumor-associated glycoprotein (TAG-72) using monoclonal antibody B72.3

Monoclonal antibody (MAb) B72.3 was generated against a carcinoma metastasis and has been shown to bind with a high degree of selectivity to a tumor-associated glycoprotein (TAG-72) found in human colon and breast carcinomas, while showing minimal reactivity to any normal adult tissues. Competition radioimmunoassays have been developed for the detection of TAG-72 in tumors and sera from both athymic mice bearing human carcinoma xenografts and patients with colon, breast and other carcinomas. The distribution of TAG-72 in human tumor xenografts was restricted to tumors originating from the LS-174T human colon carcinoma, with no significant reactivity being detected in human tumor xenografts from a different colon carcinoma, a human breast carcinoma, or a human melanoma. The levels of TAG-72 in clinical material obtained from surgery were examined; high levels were found in colon carcinomas and to a lesser extent in breast carcinomas, while no detectable levels were found in normal tissues. Sera from apparently normal patients contained a mean level of 2.2 units per ml of TAG-72. A level of 3 standard deviations above the mean level of TAG-72 found in normals was employed as a cut-off value to indicate a positive test result in subsequent studies. No patient with inflammatory disease or other benign colon disease exhibited elevated levels of TAG-72. Seven out of 20 patients with other carcinomas had elevated serum levels of TAG-72. The serum TAG-72 levels were compared with the serum levels of antigens recognized by the MAbs currently used to screen sera of carcinoma patients (CEA, GICA, and OC125). It was clearly demonstrated that TAG-72 is different from these antigens and can be found in some sera in which no antigen is detected by otherwise available MAb RIAs.     

Reactivity with patient antibodies of partially purified gp40 antigen from immune complexes in burkitt's lymphoma and nasopharyngeal carcinoma

A glycoprotein antigen (gp40) was previously identified as a major component of immune complexes isolated from sera of patients with Burkitt's lymphoma (BL) and nasopharyngeal carcinoma (NPC). In the present work gp40 was partially purified from a pool of BL/NPC sera. Sera of patients with BL and NPC as well as sera of patients with other malignant and non-malignant diseases were tested for antibodies against gp40, using a double antibody radioimmunoassay. Practically all normal sera and sera of patients with non-malignant diseases had antibodies capable of binding radioiodinated gp40. In contrast, sera of patients with BL or NPC had very low binding, while sera of patients with other malignant diseases had intermediate binding values. The low binding activity of BL/NPC sera was shown to be due to inhibition by excess gp40 present in such sera. Effusions of patients with breast or ovarian cancer also contained demonstrable amounts of gp40. The origin of gp40 is still unknown.     

Heterogeneity in the expression of HLA and tumor-associated antigens by surgically removed and cultured breast carcinoma cells

Surgically removed normal and malignant mammary tissues and human breast carcinoma cell lines were tested in binding assays with monoclonal antibodies to HLA-A,B,C antigens, beta 2-microglobulin, HLA-DR antigens, and tumor-associated antigens; the latter included a Mr 280,000, a Mr 94,000, and a Mr 85,000 membrane-bound glycoprotein and a cytoplasmic antigen. HLA-A,B antigens, beta 2-microglobulin, HLA-DR antigens, and the cytoplasmic antigen are expressed by normal mammary cells. Their malignant transformation may be associated with quantitative changes in the expression of these antigens and with the appearance of Mr 94,000 and Mr 85,000 glycoproteins. The Mr 280,000 glycoprotein was detected on only one of the breast carcinoma cell lines tested. Analysis of primary tumors and autologous axillary lymph node metastasis from 13 patients has shown differences in the expression of all the antigens tested between primary and metastatic lesions.     

Proteomics-based identification of RS/DJ-1 as a novel circulating tumor antigen in breast cancer.

PURPOSE: We used a proteomics-based approach to identify tumor proteins that elicit a humoral response in breast carcinoma and that may occur as circulating antigens. EXPERIMENTAL DESIGN: The breast cell line SUM-44 was used as a source of tumor cell proteins for two-dimensional PAGE (2-D PAGE) and for Western blot analysis in which individual sera were analyzed for primary antibodies. RESULTS: Sera from 30 newly diagnosed patients with breast cancer were screened for IgG antibodies to tumor cell proteins. Sera from 116 patients with other cancers and from 25 healthy subjects served as controls. Restricted reactivity against a set of three proteins, identified by mass spectrometry as isoforms of a novel oncogenic protein that regulates RNA-protein interaction (designated RS/DJ-1), was observed in four patients with breast cancer, but not in healthy subjects. The identity was further confirmed by Western blotting with specific antibodies. RS/DJ-1 was found to be secreted in the breast cell line SUM-44, which led us to determine whether RS/DJ-1 was found in circulation in breast cancer. Interestingly, unlike in controls, RS/DJ-1 was readily detectable in sera from 37% of newly diagnosed patients with breast cancer. CONCLUSION: The presence of autoantibodies and/or circulating RS/DJ-1 protein in sera from patients with breast cancer may have clinical utility.     

Identification of the cancer/testis antigens AKAP3 and CTp11 by SEREX in hepatocellular carcinoma

Cancer/testis (CT) antigens are considered promising target molecules for immunotherapy. To efficiently identify potential CT antigens, a testis cDNA library was immunoscreened with sera from hepatocellular carcinoma (HCC) patients. We isolated 3 different antigens, AKAP3, CTp11, and UBQLN3. Although AKAP3 and CTp11 have been previously reported as CT antigens, this is the first time that these 2 antigens have been isolated from HCC patients by SEREX. Conventional RT-PCR analysis showed that AKAP3 was frequently present in HCC cell lines (5/7) and HCC tissues (5/10), and the gene was broadly expressed in several cancer types, including breast cancer cell lines (3/6), breast cancer tissues (6/9), colon cancer cell lines (3/10), colon cancer tissues (5/6), ovary cancer cell lines (6/8), ovary cancer tissues (11/16), lung cancer cell lines (4/7) and lung cancer tissues (6/13). By phage plaque analysis, anti-AKAP3 antibody was detected in sera from 15 of 27 HCC patients and 8 of 27 healthy donors. These data suggest that AKAP3 may be useful for diagnosis and immunotherapy in HCC patients.     

Antigenic structure of normal and malignant breast tissue

The study was concerned with 13 antigens identified with the aid of a set of immune sera obtained from rabbits immunized with a nuclear, a membrane and a soluble fractions of normal and malignant mammary tissues as well as with the membranes of fat globules of breast milk. The antigens (1 nuclear, 4 soluble and 8 membraneous) were of different specificity: four--occurring in many organs, two--specific for milk only, three--organ-specific antigens which, however, persist in malignant tissues, and one--present in malignant tissue and absent from normal mammary and 25 other tissues tested. Such antigens as lactoferrin and alpha-lactalbumin were identified by immuno-enzymatic methods in the sera of a third of patients with tumors of different localizations.     

Evaluation of Known Oncoantibodies, HER2, p53, and Cyclin B1, in Prediagnostic Breast Cancer Sera

Serum autoantibodies, directed against oncogenic proteins, have been frequently detected in the sera of patients with breast cancer. It is unknown whether serum antibodies that are identified in patients with established disease could also be detected in patients with newly diagnosed disease or even predate the diagnosis of breast cancer. Using sera collected at the time of treatment, at the time of diagnosis, or before the time of diagnosis, the current study aimed to address the temporal relationship between breast cancer development and serum antibody response. Starting from serum antibodies to eight known breast cancer antigens, we first identified four serum antibodies, HER2/neu, p53, carcinoembryonic antigen (CEA), and cyclin B1, which are significantly increased in the sera collected from patients with breast cancer at the time of treatment. These antibodies were also elevated in breast cancer sera collected at the time of diagnosis. Finally, comparison of antibody responses in prediagnostic samples from women before the development of breast cancer and in controls showed that antibodies to the HER2/neu and p53 can be detected in sera that were collected on average more than 150 days before a breast cancer diagnosis. These results showed that serum autoantibodies commonly reported in sera from patients with established disease can also be detected in prediagnostic sera and may be useful for the early detection of breast cancer. Cancer Prev Res; 5(8); 1036-43. ?2012 AACR.     

Autoantibodies to an altered IgG in human breast cancer

Recent studies have shown that antibody in the serum of patients with carcinoma of the breast reacts with two distinct antigens obtained from breast cancer tissue. Hence, there are two antibodies. The first antibody reacts against the Fc fragment of immunoglobulin and is also found in the sera of patients with benign breast disease and certain inflammatory lesions and, therefore, does not seem to have any significant meaning for the patient with carcinoma of the breast. The second antibody is directed against the Fab fragment of human immunoglobulin that is found in breast cancer tissue. Recent experiments have shown that in immunodiffusion tests, this autoantibody reacts not with normal IgG(Fab), but rather with heat-aggregated IgG(Fab). It is thought that tumor-associated antibodies react with antigens on the tumor cell surface. Intracellular enzymes then proceed to fragment the attached antibody, leaving the Fab fragments attached on the cell surface. With intact immunosurveillance, the host appreciates this altered immunoglobulin (Fab). It is suggested that the autoantibody then formed against this fragment reacts with the fragment attached to the tumor cell, thereby allowing the tumor cell to be destroyed. Clinical data supporting this hypothesis are derived from the fact that 9 patients having this autoantibody to the Fab fragment are alive at 1 year after their carcinoma of the breast.