Anti-T antibody in malignant melanoma patients. Influence of response and survival following chemotherapy--changes in serum levels following C parvum, BCG immunization

Effect of linkage on the location of reducing and nonreducing sugars bound to jacalin

The crystal structures of jacalin complexed with Gal α-(1,4) Gal and Gal α-(1,3) Gal β-(1,4) Gal have been determined with the primary objective of exploring the effect of linkage on the location of reducing and non-reducing sugars in the extended binding site of the lectin, an issue which has not been studied thoroughly. Contrary to the earlier surmise based on simple steric considerations, the two structures demonstrate that α-linked sugars can bind to jacalin with nonreducing sugar at the primary binding site. This is made possible substantially on account of the hitherto underestimated plasticity of a non-polar region of the extended binding site. Modeling studies involving conformational search and energy minimization, along with available crystallographic and thermodynamic data, indicate a strong preference for complexation with Gal β-(1,3) Gal with the reducing Gal at the primary site, followed by that with Gal α-(1,3) Gal, with the reducing or non-reducing Gal located at the primary binding site. This observation is in consonance with the facility of jacalin to bind mucin type O-glycans containing T-antigen core. © 2016 IUBMB Life, 68(12):971-979, 2016.

Crystal structure of the jacalin-T-antigen complex and a comparative study of lectin-T-antigen complexes

Thomsen-Friedenreich antigen (Galbeta1-3GalNAc), generally known as T-antigen, is expressed in more than 85% of human carcinomas. Therefore, proteins which specifically bind T-antigen have potential diagnostic value. Jacalin, a lectin from jack fruit (Artocarpus integrifolia) seeds, is a tetramer of molecular mass 66kDa. It is one of the very few proteins which are known to bind T-antigen. The crystal structure of the jacalin-T-antigen complex has been determined at 1.62A resolution. The interactions of the disaccharide at the binding site are predominantly through the GalNAc moiety, with Gal interacting only through water molecules. They include a hydrogen bond between the anomeric oxygen of GalNAc and the pi electrons of an aromatic side-chain. Several intermolecular interactions involving the bound carbohydrate contribute to the stability of the crystal structure. The present structure, along with that of the Me-alpha-Gal complex, provides a reasonable qualitative explanation for the known affinities of jacalin to different carbohydrate ligands and a plausible model of the binding of the lectin to T-antigen O-linked to seryl or threonyl residues. Including the present one, the structures of five lectin-T-antigen complexes are available. GalNAc occupies the primary binding site in three of them, while Gal occupies the site in two. The choice appears to be related to the ability of the lectin to bind sialylated sugars. In either case, most of the lectin-disaccharide interactions are at the primary binding site. The conformation of T-antigen in the five complexes is nearly the same.

Red blood cell polyagglutination: clinical aspects

Polyagglutination is the term applied to red blood cells (RBCs) that are agglutinated by almost all samples of human sera from adults but not by autologous serum or sera of newborns. The polyagglutinable state may be transient or persistent. Transient polyagglutinability results from the exposure of normally cryptic antigens by bacterial enzymatic activity during the course of an infectious process. RBCs are polyagglutinable because most sera from adults contain agglutinins for the exposed antigens. This type of polyagglutination can often be reproduced in vitro with bacterial culture fluids or isolated enzymes. Persistent polyagglutination may be a consequence of somatic mutation leading to a cellular lineage characterized by an enzyme deficiency that results in exposure of a normally cryptic antigen, Tn. Most human sera contain anti-Tn. Tn polyagglutination is regularly accompanied by leukopenia and thrombocytopenia and has been associated with leukemia. Other forms of persistent polyagglutination are due to the inheritance of rare blood groups or are associated with a hematologic dyscrasia.

Tumor marker disaccharide D-Gal-beta 1, 3-GalNAc complexed to heat-labile enterotoxin from Escherichia coli

Heat-labile enterotoxin (LT) is part of the cholera toxin (CT) family and consists of a catalytic A subunit and a B pentamer that serves to recognize the oligosaccharide part of the GM1 ganglioside receptor. We report here the crystal structure of heat-labile enterotoxin in complex with the disaccharide portion of the Thomsen-Friedenreich (T-antigen) tumor marker. The toxin:carbohydrate complex is determined to 2.13 A resolution, yielding an R-factor of 18.5%. The T-antigen disaccharide, D-Gal-beta 1,3-GalNAc-Ser/Thr, is present in more than 85% of human carcinomas and monitoring its autoimmune response is used for the early detection of tumors. Insight into the molecular recognition of this tumor antigen by sugar binding proteins can benefit the development of a diagnostic tool for human carcinomas as well as a T-antigen directed anticancer drug delivery system.

Anti-Thomsen-Friedenreich (T) antibody-based ELISA and its application to human breast carcinoma detection

An anti-Thomsen-Friedenreich (T) antibody-based enzyme-linked immunosorbent assay (ELISA) with high efficacy in human breast carcinoma detection is described. Immunoreactive T epitopes occur in approximately 90% of all carcinomata; all humans have anti-T antibodies, naturally occurring anti-carcinoma antibodies, induced by their own intestinal flora. Carcinoma patients, but not control subjects, show alterations of serum anti-T hemagglutinin levels. Human anti-T antibodies are predominantly IgM. In the protocol presented here, anti-T IgM antibodies are quantitated by ELISA using Immulon 2 wells coated with human blood group O erythrocyte-derived T antigen as solid phase; in addition, total IgM in each serum is quantitated by ELISA in parallel with the anti-T IgM. Inter-assay coefficient of variation was 2% for both ELISAs. Although anti-T IgM values alone distinguish between carcinoma patients and control subjects, use of the quotient, QMe, which also considers total IgM, increases this distinction. For a given serum, QMe was obtained by the formula: QMe = (100 x (anti-T IgM)2/total IgM). Sera of 242 subjects, 117 breast carcinoma patients, 36 benign breast disease patients and 89 healthy persons were analyzed. QMe identified 88% of the breast carcinoma patients: it all six (100%) in situ, 11/13 (85%) Stage I, 48/58 (83%) Stage II and III and 38/40 (95%) Stage IV patients. Sera from 83% of the 36 benign breast disease patients were negative, i.e. within normal range; five of the six positive sera originated from patients with increased long-term risk of breast carcinoma, while sera from 11 other patients with increased carcinoma risk were negative. Overall, 90% of the 125 non-carcinoma control subjects were negative by both anti-T IgM and QMe. In preliminary studies, the ELISA protocol detected 11/14 (79%) patients with carcinomata other than those of the breast. The identification of all six in situ breast carcinoma patients by QMe points to its usefulness in carcinoma detection, especially early.

Association of Helicobacter pylori gastric infection with the suppressed Thomsen-Friedenreich antigen natural humoral response

BACKGROUND

A low natural humoral immune response to Thomsen-Friedenreich antigen (TFA) is a general phenomenon in patients with cancer, including gastric cancer, and in some premalignant conditions. It has been also shown that Helicobacter pylori infection is associated with increased risk of gastric cancer. The possible link between the TFA immune response and H. pylori infection was investigated.

METHODS

Enzyme-linked immunosorbent assay with H. pylori cell surface glycine extract as antigen and microhemagglutination of neuraminidase-treated blood group O donor erythrocytes were used for evaluation of IgG H. pylori antibody and TFA agglutinin levels in sera from patients with gastric cancer (n = 39) or ulcer of the stomach (n = 36) and controls (n = 49).

RESULTS

The tendency to an inverse relationship between the two events was found in all groups studied, including cancer. H. pylori-seronegative persons had higher TFA natural antibody titer than the related H. pylori-seropositive groups. When log2 of TFA antibody titer > 4 for strong TFA responders and H. pylori relative antibody activity > 25 for H. pylori-seropositive persons were chosen as cut-off limits, the association was statistically significant (p < 0.02). TFA antibody level was decreased in cancer patients as compared with controls (p < 0.002). No relation to age, stage of the disease, or tumor morphology was noted.

CONCLUSION

The data suggest that the TFA natural immune response, which is known to participate in tumor-host relationships, is also involved in H. pylori-host interactions, probably as a natural factor of resistance against H. pylori infection.

T/Tn antigen vaccine is effective and safe in preventing recurrence of advanced human breast carcinoma

For nearly 20 yrs, we used T/Tn antigen vaccine in safe, specific, effective, long-term intradermal vaccination against recurrence of advanced breast carcinoma. Treatment is ad infinitum. All 18 breast carcinoma patients treated, pTNM Stages IV (6), III (6), and II (6), survived > 5 yrs postoperatively; 10 survived > 10 to > 18 yrs; of the latter, three patients each are Stages III and IV. Five additional 5 yr survivors have not yet reached 10 yrs. The probability that our survival results are due to chance, with NCI "1991 Standard PDQ Data" as control, for all three stages taken together is: 5-yr survival: p < 1 x 10(-8); 10-yr survival: p < 1 x 10(-5). There were no untoward side effects. The vaccination area presented as a delayed-type hypersensitivity reaction, but at variance with the PPD reaction, with significant inflammation, increase of helper T lymphocytes and decrease of the T suppressor/cytotoxic cell ratio.

Exposure of cryptantigens on erythrocytes in patients with breast cancer

One hundred thirty-two patients with breast cancer were examined for exposure of cryptantigens on their erythrocytes (RBC) using a lectin panel consisting of Arachis hypogaea and Glycine soja. Eight had exposed cryptantigens; of the eight, five were classified with additional lectins as T-polyagglutination type and three as Th-polyagglutination. A control group of 300 healthy blood donors had no exposed cryptantigens on their RBC. These findings could not be correlated with the staging of the tumor, extension of metastases, or positive estrogen or progesterone receptors of malignant tumor cells. Only one study has been found that describes the incidence of agglutination of erythrocytes from cancer patients using a monoclonal antibody, which detected an epitope on the RBC from cancer patients and was considered to be distinct from the antigen bound by naturally occurring anti-T. Studies have been made describing polyagglutinable sites on breast cancer tumor cells, where there was a much higher incidence. This discrepancy can be explained either by a difference in the methods used to search for cryptantigen exposure on the various types of cells, or by the existence of a different mechanism, which causes the exposure of cryptantigens on RBC as opposed to malignant breast tumor cells.

T and Tn, general carcinoma autoantigens

Primary and metastatic carcinomas are epithelial in origin and comprise by far the largest group of malignant tumors in humans. In most of these tumors, T and Tn antigens, whose epitopes have been synthesized, are uncovered and immunoreactive. In all other tissues T and Tn antigens are masked and not accessible to the immune system; they are generally precursors in normal complex carbohydrate chains. Thus, carcinomas have antigens recognized as foreign by the patients' immune system. The expression of T and Tn antigens has pathogenic and clinical consequences, and the antigens themselves are powerful histological markers in carcinoma diagnosis and frequently in prognosis. Most patients distinguish their carcinoma from all other cells, as shown by strong autoimmune responses to T antigen. These responses are readily measured by assays, and they allow detection of carcinomas with greater sensitivity and specificity frequently earlier than previously possible. Moreover, the extent of T and Tn expression often correlates with carcinoma differentiation; on a molecular level, clustered T- and Tn-active structures on carcinoma cell surfaces may be involved in invasion.

Patients' immune response to breast and lung carcinoma-associated Thomsen-Friedenreich (T) specificity

We report here sensitive and specific measurement of immune responses of patients with certain kinds of carcinoma toward the physically and chemically well defined T antigen isolated from healthy human erythrocytes. Over 90% of adenocarcinoma tissues tested possess T-specific immunoreactive structures as determined with human antisera, in contrast to healthy tissues and benign lesions. Adenocarcinoma patients recognize the carcinoma-associated T antigen as foreign. Delayed-type skin hypersensitivity reaction to T antigen (DTHR-T) was positive in all 25 lung adenocarcinoma patients tested, in 88% of 101 patients with ductal, in 43% of 30 patients with lobular or tubular breast carcinoma and in 9/9 patients with adenocarcinoma of body cavities. Patients of all Stages reacted positively. All 7 patients with small cell lung carcinoma and 3/5 with malignant melanoma had a positive DTHR-T. None of 17 patients with malignant brain tumors, leukemia or Hodgkin's disease, sarcoma or thyroid carcinoma reacted. The DTHR-T was specific in that all 77 healthy persons and 48/49 with other diseases, including 23/24 with non-cancer lung disease were negative; one patient with organizing interstitial pneumonitis was positive. This points to a possible source of false positive reactions. 91% of 149 patients with histologically benign breast disease had a negative DTHR-T; the histology of some of the positive ones was reexamined, 2 proved to have carcinoma in situ.